On Friday, Microsoft released Windows 7 Beta and the response was overwhelming. Literally. Initially, there was a plan to limit the number of beta participants to 2.5 million, but per the Windows team blog:

Due to an enormous surge in demand, the download experience was not ideal so we listened and took the necessary steps to ensure a good experience. We have clearly heard that many of you want to check out the Windows 7 Beta and, as a result, we have decided remove the initial 2.5 million limit on the public beta for the next two weeks (thru January 24th). During that time you will have access to the beta even if the download number exceeds the 2.5 million unit limit. 

You can download the ISO for the beta here - 

http://www.microsoft.com/windows/windows-7/default.aspx

The good folks over at ZD Net have provided some info on how to burn the ISO, as well as provide guidance on how to get the Windows 7 Beta installed via Virtual PC 2007. That article can be found here: http://blogs.zdnet.com/hardware/?p=3317

As someone who's been using the pre-beta and the beta, I'd encourage you to check it out. It's incredibly stable, fast, and has a number of cool new features.