If you uncheck the Check to see if the site I'm visiting might be a scam option and then recheck it, you get a wordy dialog explaining that you'll send data to Google's log about fishy pages. When we tried to switch between local and by asking, the only choice was Google, and that was grayed out.

We were unable to find a site that tripped this tool after setting it to run. We threw every URL from patently spam emails we could find. Perhaps we really did win a million euros or owe that eBay user's PayPal account for that $465 we don't remember bidding on. Even if we entered a URL that was known to be a phishing site, found on security sites that keep track of such things, we couldn't trip the feature.

The spellcheck for text boxes was an interesting frill, using the familiar dotted colored lines under words of questionable orthography. In Firefox, zoom only zooms text, not pictures, but there's a wider range of text sizes to zoom to than in IE6.

RSS feeds are nicely handled in Firefox. When you navigate to a site that contains an RSS feed, the little orange feed button will appear in the right side of the address box. Clicking this brings up the following page: The answer you always hear when discussing a missing feature in Firefox is, "You can do it with an Extension." That usually is the case, and the Firefox Extension capability is elegant, powerful, and easy to use:

The link in this dialog goes to a full, organized guide of available extensions.

It's also nice that Firefox offers Themes:

But all the themes we found merely changed the interface buttons and perhaps added an image to the top menu area; they don't change the window borders the way you can with WindowBlinds. And beware that most themes haven't yet been updated to work with Firefox 2.

With XUL, AJAX and other technologies, Firefox has the most programmable interface of the browsers, allowing developers to pretty much use it as a foundation for their web-based applications. One example is the limited word processor from Michael Robertson's new company Ajax 13, ajaxWrite.

One peeve: Why isn't there still a one-click button (by default) for adding a new tab? You can use the middle mouse button if you know about it—and if your mouse has one (laptop users need not apply)—on new links, but sometimes you want a new empty tab, which in Firefox requires going through menus, or double clicking on the empty space to the right of the last tab (if you knew about that—usability is about making needed features obvious).

Addendum: Several readers have pointed out that you can customize the toolbar with an Add Tab icon, but this ain't the default, and it's not right there next to the tabs.

The security and tabbed browsing brought people to Firefox, and the extensions are what keeps them there. But it's a question of whether you're the type of person who likes to tinker with things to get them just how you want them, or to have something that comes with all the options built in. Extensions, themes, and interface programmability make Firefox the most flexible browser out there. But this programmability and its tremendous market share increase make it a target for security threats, which to their credit, the Firefox community of developers has addressed with a security updates.

If you really want to see a version of Firefox that's revamped, check out the Gecko-based Flock, which has added Web 2.0 features like tags, mashups with photo sharing and social bookmarking sites, and blogging. Flock also has implemented interesting interface features like a star button for quick favorite adds to both local and shared online sets, a topbar for browsing pictures, and a blog editor. Continued... Microsoft's major themes for the new Internet Explorer are "easier and more secure." We think catching up to the competition with stuff like tabbed browser windows, add-ins, and built-in search is probably also pretty high on the agenda, too. And it's a major overhaul from Version 6. The beta browser sports a new, slick, streamlined look:

Note that by default, IE7 dispenses with the standard menu choices at the top, instead using icons with drop-downs. The star button lets you easily add a site to your Favorites, but only locally, unlike Flock, which can simultaneously save them to an online social bookmarking site like del.icio.us. Also, the refresh and Home buttons have moved over to the right of the address box. We're not sure we love that, but we're sure they have the usability testing numbers to justify it.

Tabbed browsing is fairly well-done in IE7, and you can even turn it off if you're an old-fashioned sort:

You have to hover over the blank, small tab to the right of the active ones to create a new blank tab; we wonder why this isn't always visible?

One feature unique to IE7 is its tile view of your tabs, called Quick Tabs, accessible from an icon just to the right of the add favorites icon:

Unlike the other two browsers in this roundup, IE7 has an RSS button that's always there below the address bar. If a site contains a feed, the button turns orange and lets you subscribe. Presentation of feeds is nicely done:

The entries could be a bit more tightly laid out, and the browser even includes links to Digg and del.icio.us for each entry—the feed has to include these links.

IE7 doesn't have quite the add-on library that Firefox has, and many of the "add-ons" are things like toolbars and even standalone apps. Oddly, we even found an entry for the Opera Browser among IE7's list of Add-Ons. Also, most of the add-ons don't customize the interface as they do in Firefox, and there aren't as many fun ones as there are in Opera Widgets.

Page zoom is much improved in IE7. In addition to holding down the Ctrl key and spinning the mouse wheel in and out, there's a zoom control in the lower right corner of the screen (see first picture of IE7). In Version 6, you could only zoom among the five text sizes, but in 7 you can zoom the page and pictures over a ridiculous range of small and large size, and the scroll bars zoom along with the browser contents.

IE7 adds some welcome conveniences for printing, too: It scales pages so they don't cut off on the side of the page—we've all run into this when printing web pages.

Security
IE has been possibly the biggest target of security attacks over the last decade, with updates to cover holes a regular occurrence. Since Bill Gates's edict demanding "trustworthy computing" in 2002, Microsoft has been making big efforts towards eliminating these security holes, and IE 7 is intended to be a model child of this initiative. Defender, now in beta 2, is the major salvo in this direction; it's anti-spyware software that both finds spyware on your system and monitors for it in real time while you browse with IE.

According to Microsoft, the following security features are to be found in IE7:

• ActiveX Opt-in
• Security Status Bar
• Phishing Filter
• Cross-Domain Barriers
• Delete Browsing History
• Address Bar Protection
• International Domain Name Anti-spoofing
• URL Handling Security
• Fix My Settings
• Add-ons Disabled Mode
• Features Unique to Windows Vista

And when Windows Vista rolls around, they also plan to add a Protected Mode (where IE runs in its own sandbox) and Parental Controls. When went to some questionable sites, we could see the little animated icon in the lower right doing its job; hovering the cursor over it yielded the tooltip: "Phishing Filter is checking this website." It also caught a website that was trying to install an add-in.

In his column of a couple months ago, Jason Cross has said that IE7 Isn't Good Enough. His main complaints are that the new browser has taken too long to launch, and that it doesn't support the middle mouse button. This reviewer agrees that Microsoft should not have sat on its market-share laurels for five years without producing a new version of IE, but that doesn't mean the new browser doesn't include major advances. If the Firefox 2 beta is any indication, that browser won't be wowing anyone with incredible new features that would send it way ahead of the new IE version any time soon. As to the middle mouse button, it is a nice feature, but we're not sure what percentage of users even know of its existence.

Microsoft doesn't expect to convert the Firefox religious, but rather to bring over those who might have abandoned IE because of its security problems and lack of a tabbed interface. IE7 is a fine effort in this direction. Continued... The Norway-based Opera Software has made a bigger dent in the mobile browser market, with deals for its Opera Mini with T-Mobile and Sony Ericsson, and recently with Nintendo being chosen as the browser on the Wii.

Opera was the first browser of all to feature tabbed browsing windows, debuting them in 1995. We think the browser does a darn good job implementing tabs in terms of usability and visibility, as well. The clear "Add new tab" button, and the default ability to close every tab—and now, when you hover the cursor over a tab, you get a thumbnail of the site on that tab—all show Opera to be a forerunner in the tab department. Of course, we're sure there are Firefox extensions that enable these behaviors, but having them built into the default application is nice.

Opera is the only non-beta in our roundup, and its new features include widgets, content blocking, BitTorrent, and a search engine editor.

Even in some features other than tabs, the other two market-leading browsers are playing catch-up with Opera—built-in RSS reader and saving groups of open tabs for later sessions, zooming text and pictures, and the X on each tab to close it. Here's the complete list of what its makers say is new in Opera 9:

• Content blocking
• BitTorrent support
• Widgets
• Search engine editor
• Site preferences
• New installer. One package—30 languages
• Integrated source viewer
• opera:config for advanced settings configuration
• Tab use best: Thumbnails when you hover the cursor over a tab.

Widgets in Opera are more like small standalone applications that can interact with the internet and live outside the browser, rather than interface elements that can change the basic behavior of the browser, as Firefox's extensions are.

The new BitTorrent support in Opera 9 is fairly unobtrusive; you simply go to a BitTorrent index web site, and when you click on a torrent link (a URL ending with the .torrent extension), you'll get this dialog:

After you give this the OK, your torrent will start downloading, and will appear in the regular Transfers page. There's also a dropdown choice in the built-in search to help you find torrents without the need to find a separate torrent search page.

On the topic of basic interface elements, we got a lot of use out of the sidebar in Opera pulls out when you click the left edge of the window. This can display bookmarks, history, widgets, notes, transfers, and links on the current page. Pretty darn handy.

And Opera still boasts several unique conveniences like Mouse gestures, and the Fast-forward button, which finds the most likely Next Page link and takes you there. Mouse gestures aren't for everyone, but they can save you keystrokes with a little practice. One simple example: To go back to the previous page, hold down the right mouse button and click the left mouse button. Fast forward worked perfectly on ExtremeTech reviews, finding the next page easily without requiring you to hunt for the Next link. A personal favorite convenience in Opera is Paste and Go, which lets you paste a URL into the address bar or a search term into the search box and load it in one click: It's the kind of thing that's so obvious but someone had to think of actually doing it. Paste-and-go is also available as a choice from the right-click context menu and as a keyboard shortcut.

One small convenience that was missing in Opera and that this reviewer has used frequently in Internet Explorer and Firefox is hitting Ctrl-Enter to add the "www." and ".com" to your entry on the address bar and just go to that URL by typing the meat of the domain name. We're happy to see that the shortcut now works in Opera 9. Rounding out the navigation aids: Middle clicking the mouse scroll wheel can close a tab and open a link in a new tab, and you can choose whether to have an X on all tabs to close them.

Another nice little touch in Opera is the progress bar at the right of the address bar, which tells you what percent of the page and the number of images that have been loaded from the site. The other browsers have progress bars, but we like the extra information here.

One oddity about Opera is that it opens popups that you want within the same browser frame, instead of in their own windows; this behavior can be changed in Advanced Preferences dialog, however.

Opera was the first browser with tabs, support RSS support, and now it's the only one with a built-in BitTorrent client and tab thumbnails (though IE7's Quick Tabs almost serves the same function). It's still the only with a fast-forward button and mouse gestures, and there are lot of other little conveniences that its developers cleverly incorporated—one-click Paste-and-Go, for example. Add to this that it's the fastest to load in testing and does best on the Acid2 web standards test, and we have to scratch our heads as to why its market share among browsers isn't greater. Continued... We tested memory usage for the browsers both empty and with six tabs loaded. We also compare the last released versions of Firefox (1.5) and Internet Explorer, where pertinent. Memory and disk tests were done on a Pentium D system at 3.2GHz with 2GB of RAM, running Windows XP Professional with Service Pack 2 installed and load speed tests on a Sony Vaio 1.5GHz Pentium M system with 512MB RAM. Before we took the measurements, we executed the command rundll32.exe advapi32.dll,ProcessIdleTasks.

With no pages loaded, and with no bookmarks, and otherwise with default download settings, here was the memory use for each of the browsers: