I’m not using Internet Explorer 7 at all but I know some guys who like it so much that they might ditch Firefox for it. The new Internet Explorer 7 has basically the same functionality and expandability as Firefox. You can download add-ons for Internet Explorer 7 to add functions to it. The Windows Marketplace lists more than 550 add-ons for Internet Explorer 7. The major difference that I can see is that Microsoft offers free and commercial add-ons for Internet Explorer 7 while I do not know of a single Firefox add-on that is commercial. (correct me if I’m wrong)