Just saw on Ben’s blog that Virtual PC 2007 is now available for download. I have been using it since it went Beta in October. I find it works fine and ran Windows Vista pretty good too. Of the new features, PXE boot is now supported which is nice to play with to learn WDS and the hardware support for virtualization is nice too.
Download: http://www.microsoft.com/windows/products/winfamily/virtualpc/default.mspx