Installing IE 7 requires a reboot and takes forever. Plus the download is giant, and you have to turn off your virus scanner. My installation went smoothly, but I got the feeling IE was reprogramming my computer’s DNA as it worked.

The IE 7 installer asks users to temporarily disable their antivirus and antispyware protection, which doesn’t inspire confidence. Installing IE 7 requires Windows validation, a restart, and a connection to Microsoft servers, which significantly slows down the process.

IE 7’s installation recommended that we back up important files, close all programs, and eventually restart, while Firefox asked us only to close the old Firefox. And Microsoft checked that we were running a valid copy of Windows XP before we could download IE 7, which felt intrusive (if not insulting) next to the hands-off Firefox installation. But I’m not crazy about IE 7 or Firefox creating browser icons by default for my Windows XP desktop, Start Menu folder, and Quick Launch bar; you’ll have to uncheck those during installation if you don’t want the shortcuts.

Firefox, on the other hand, is a small download and installs in about 30 seconds, no reboots or gene sequencing required.

Installation of Firefox 2 was much faster and easier, completing in a minute or two. It scanned my old version for incompatible extensions, then updated any that were available. Firefox 2 did not include my custom-created search engines, only those defaulted by Mozilla. Any custom engines need to be manually moved into the Searchplugins directory.

Firefox was a faster download, plus it migrated every toolbar and all but one of my dozen bookmarklets from Firefox 1 without a hitch.

With the latest versions, both browsers treat tabs similarly. You can close tabs with their own little close boxes and open new tab windows by clicking in the tab bar (IE 7 makes it more obvious by displaying a tiny, empty tab). Both highlight the active tab subtly (too subtly for my taste), and let you drag tabs around and save open tabs. Differences: Firefox makes it easy to reload all tabs; IE has a thumbnail viewer.

IE 7 includes a New Tab button to the right of your last open tab that takes up unnecessary screen space. I couldn’t find a way to remove it. IE 7 bunches two Favorites icons, all open tabs, and the standard browser toolbar in the same row of real estate. A helpful tab preview icon displays thumbnails of all your open tabs for any window.

Is it my imagination, or does Firefox open a new tab about a millisescond faster than IE 7 does? At the same time, IE 7’s blank tab can help users discover tabbed browsing.

One change in Firefox 2 that is a step backward from the last version: If you open a lot of tabs, Firefox shrinks their size a little and puts arrows at the left and right of the tab bar so that you can scroll back and forth. The previous version shrunk tabs a lot, so you could fit many more into the tab bar. I’m dinging Firefox’s score for that one. IE 7 has the same problem.

Firefox adds a new Close Tab button to each open tab but didn’t add thumbnail previews (a feature that can be added via Firefox extension). It would be nice to incorporate more features from Tab Mix Plus, such as the ability to customize how Ctrl-Tab switches tabs.

Firefox’s tiny drop-down menu next to its tabs is a convenient shortcut for finding recently viewed pages, and its layout offers more room for tabs–although once we had a dozen tabs open, we were forced to scroll awkwardly to view the thirteenth tab and beyond. Luckily, though, if Firefox crashes, you can restore those tabs, which IE 7 can’t do.

There are fancy little flourishes in both browsers (IE has page zoom; Firefox has a spelling checker), but the big news in new browser features right now is RSS reading. Both browsers recognize when a page has an RSS feed, and both will parse XML and display a readable page instead of code when they see it.

RSS feeds: Once you’ve subscribed to a feed via IE 7, it’s easy to see, sort, manage, and read your subscriptions from a two-panel interface. Firefox’s Live Bookmarks do a similar job, but not as neatly. I only wish IE 7 detected available feeds better.

Neither IE 7 nor Firefox do a terrific job of showing off their new features. Many of IE 7’s new features are old tricks for Firefox. At least IE 7’s RSS icon gave us a hint about its ability to surface newsfeeds; that icon appears within the Firefox address bar only when you land at a Web site with an RSS feed. But once we subscribed to some feeds, we couldn’t find them within IE 7. Firefox, on the other hand, displayed them by default on a toolbar and within its Bookmarks folder.

Firefox does a much better job of managing feeds: It will let you subscribe in Firefox’s own reader, which awkwardly makes bookmarks of headlines, or in Google, Bloglines, Yahoo, or any reader application you have on your PC. IE will subscribe itself only to feeds, and it doesn’t display RSS content as reliably as Firefox.

In Firefox 2, I love the Manage Search Engines dialog, but I’d say the Session Saver feature is the biggest improvement. I know that many people who accidentally quit the browser will love it.

Firefox’s RSS features are even more flexible since (as Rafe mentions) they can let you subscribe with a third-party newsreader. Overall, however, I found the RSS features somewhat clumsy in both browsers and easy for RSS newbies to overlook. IE 7’s easy ability to zoom in on a Web page makes for better browsing if you have vision problems. Ctrl-T does the same trick within Firefox, but most users may not memorize such keyboard shortcuts. Firefox also checks your spelling, which could save you from embarrassing yourself in a hasty e-mail or blog post.

I have to defer to security gurus in this category. Historically I’ve been impressed with how seamless installing security patches to Firefox has been. As far as privacy, both products now let you quickly erase tracks from your browser, which is good.

A phishing filter within IE 7 checks the Web pages you visit using heuristics and a whitelist of legitimate sites. IE 7 lets you clean out your history, temporary files, and Web cookies with one button, but it’s not easy to delete specific files in those groups. Another nice browsing-security touch is the “Web page privacy policy” feature. The past history of exploitable security holes in IE is a factor to consider.

At least during setup, IE 7 appears to care about security by giving you the choice to install a phishing filter. Firefox doesn’t make its security offerings obvious during setup. Both browsers allow you to clear cookie crumbs that show the sites you’ve seen, but we found such features tricky to find within IE 7’s new interface.

Firefox makes it a one-click operation, though, which is much better. On the other hand, it’s far too easy to reveal all your stored passwords in Firefox. You can put (another) password in front of this feature, but most people won’t, leaving their passwords easily visible to anybody who gets on to their PC.

Also adding antiphishing measures, Firefox 2 offers a choice to check sites from a preexisting blacklist or via Google. Firefox 2 also offers more customization than IE 7, letting you specify which warning messages you’ll receive and allowing you to view all your cookies in a list.

Firefox’s stronger reputation for security and Mozilla’s practice of addressing vulnerabilities soon after they’re discovered precedes its latest update.