Virtual Server R2 for free

First it was VM Ware.
Now you can get Virtual Server R2 also for free from Microsoft.
Thanks to Damir Tomicic for pointing it out.

Actually some years from now there will be a time when Windows itself will be running on virtual machine along with .NET framework and others. But still this is a good opportunity to start using virtualization of Windows right away.
For more info, check this post from Virtual PC guy.