Many of you use Virtual PC and Virtual Server, but not many people are aware of some new hotfixes and security updates released in 2009. Before getting to those, the latest versions of those two products are Virtual PC 2007 Service Pack 1 and Virtual Server 2005 R2 Service Pack 1. You first need to be at that level. Here is a hotfix rollup for Virtual PC 2007 SP1:
http://support.microsoft.com/kb/958162 released February 20, 2009
This is a security update for Virtual PC 2004, Virtual PC 2007, Virtual PC 2007 SP1, and Virtual Server 2005 R2 SP1:
http://support.microsoft.com/kb/969856
If you are running Windows 7 on a machine that doesn't support hardware assisted virtualization, you'll need to use Virtual PC 2007 SP1. It works just fine. You don't have to run Windows 7 Virtual PC. Of course, if you can run the Windows 7 version, you should. Microsoft has a utility to let you know if your machine supports hardware assisted virtualization: http://www.microsoft.com/downloads/details.aspx?FamilyID=0EE2A17F-8538-4619-8D1C-05D27E11ADB2&displaylang=en