In Betanews tests involving Web browsers running on both operating systems on the same computer, the speed increase was definite and measurable.
I am surprised to hear how each browser does better in Windows 7. I am currently trying Google Chrome, and it is pretty good. Alot faster than IE8, but missing some features, like highlight some text, print, print selected. So it is either all the text or not to print at all. The new 3.0 beta version allows extensions. I hope RoboForm adds support for Chrome soon too! Another down side is that in the bookmarks, there is no -> arrow to open all webpages in the bookmark folder, I have to right-click, open in new tab. I also am not able to use a program like IEPro to add spell checking to forms. Some websites will not work with Chrome, and will have to use IE or FireFox. I never really got into using FireFox, and think it takes a while to load. My Suggestion, is to try each of them, and see how they work.