For those of you like me who don't like installing additional software for tasks your computer is already equipped to do, IE9 is now final and released. That said, it's probably highly recommended you install IE9 even if you don't use it just to keep your computer up to date and plug any potential security holes.
http://www.beautyoftheweb.com/
(Yes, that's really the address.)
I've been using IE9 in beta for months, it works great. The rendering and javascript is now Chrome-fast, the tracking protection can import the Adblock Plus list, and it finally has a download manager (with resuming). The "one row" address bar + tabs takes a little getting used to but you can force them back onto a separate toolbar row if you really want to, it looks ugly like that though.
I'm going to assume that computers will start trying to automatically install IE9 through Windows Update in the not too distant future anyway.
Note: You can not install IE9 on Windows XP. It's 10 years old, get Windows 7 already.