For Vinovin (with apologies to Dunlop):
From what I've read, IE7 has partly caught up with Firefox. (I'm happy to stick with IE6 for the odd site which will only load with Microsoft programs, so I don't know exactly what IE7 does). Firefox, though, has long been the leader in reducing security risks and was way ahead of IE in such things as using tabbed browsing, a built-in pop-up blocker and an integrated download manager.
For me, however, the greatest advantage of Firefox is that, although it takes longer to load than IE, the actual time for pages to download and display is greatly reduced. I also find it easier to manage and back-up bookmarks with Firefox. (Firefox stores bookmarks a a single HTML page, rather than as a set of shortcuts. If you switch from IE, you can automatically import all of your IE bookmarks at installation, or at any time later).
Firefox also includes an integrated search tool. This uses Google by default but can be configured to use any search engine. Some Firefox users find that they obtain great benefits from the many 'add-on' features which can be downloaded, although I don't use them myself.
Firefox is free and is the world's most popular browser. (That, of course, assumes that you define 'popular' as requiring an element of choice in the decision to use particular software, rather than simply using whatever is already on the PC).
Firefox doesn't conflict in any way with IE, so there's no reason why you shouldn't give it a try. (i.e. both programs can sit side by side on your PC and, if you want, run simultaneously. You don't have to uninstall IE to use Firefox). So, you've nothing to lose by giving Firefox a try:
http://www.mozilla.com/
Chris