Virtual Server 2005 gives you the opportunity to run a guest operating system on your desktop box. This is especially handy if (like me) you have a 'business' box, but want to do some development using the latest tools. Up to this point, I've been using Microsoft Virtual PC (VPC) with great success. VPC is cool, but the additional features and flexibility with Virtual Server 2005 make it well worth evaluating.
Oh. It's now available as a free download.
Oh. It's also certified to run Linux as a guest operating system.
Visit the Windows Server System Virtual Server Page.