Almost the same as the ubuntu post, but I have more to say on the windows edition.
Microsoft thought that they had the all in one browser, but sadly they didn't!
IE9 is only compatible on windows vista and windows 7, due to "graphics and performance changes than to windows xp"
xp Was left out by Microsoft, But firefox came and said: "we will not tolerate that windows xp users are left out of the HTML 5 web beauty" although it wouldn't really work on xp cause of it lack of graphics performance, they didn't hassle do code firefox for windows xp also (by the way it works good on windows xp)
Download now for windows:
http://www.mozilla.com/en-US/firefox/fx/