Use Virtual PC, then you need this site!.

Absolute goldmine, lists every OS you can image and provides details on whether its works on Virtual PC.  I was pretty amazed by the list, especially compared with VM Ware.  Where a product has issues it also has notes of workarounds.  Even better if you want to keep up to date with the latest additions there is an RSS feed.

Also if like me you have VMWare Workstation, GSX Server and VPC then this is a good review to help you decide which to use.  I also suggest checking out the comments on the review.