IE finally supports tabbed browsing! It’s a mixed bag, though: while it trumps Firefox with handy thumbnail page previews and support for multiple-tab homepages, it lacks simple features such as quickly restoring a closed tab.

The interface has been tweaked, with the address bar moved to the top and the refresh and stop buttons to its right, completely changing the way you use the browser. We didn’t much care for having to disable AV protection during installation, or the forced reboot either. This is apparently to install the RSS engine to the system kernel and, on balance, the new RSS reader is ultimately worth it. However, Firefox still handles RSS more elegantly through its Live Bookmarks feature and the ability to associate feeds with third-party readers. The Favorites Center replaces the old sidebar, integrating bookmarks, RSS feeds and browsing history in a single, compact window.

You can now shrink Web pages to fit the printed page, and there’s support for third-party add-ins. These aren’t yet as useful as Firefox extensions, though, simply because there are fewer of them, and many carry a fee. But underneath it all, IE7 is still powered by the IE4 rendering engine and it shows in a relatively slow performance. It still doesn’t fully support CSS 2.1 either, and totally fails the Web Standards Project Acid2 test. In fairness, so does Firefox 2, but by a much narrower margin.

Security is where IE7 comes under scrutiny, as it reuses much of the code from IE6 still awaiting patches. Anti-phishing protection is welcome, and we approve of the requirement to opt in when using ActiveX components rather than them installing automatically. Although there are some built-in code protections against cross-domain scripting exploits and malicious URL handling, you’ll need to wait for the Vista version of IE7 to get sandboxing of all sessions.

While IE7 is a big improvement over IE6, Firefox leads the way. With its inline spellcheck, automatic session restore and data-privacy features, only Microsoft fans should stick solely to IE.