I use both of these application day in and day out. So when these updates products get an update to support new guest with service packs than you just gotta get the update!
Virtual PC 2007 SP1
Virtual PC 2007 SP1 adds support for Windows Vista SP1 and Windows XP SP3 as both host and guest operating systems. It also adds support for Windows Server 2008 Standard Edition as a guest operating system.
Virtual Server 2005 R2 SP1 Update
This update to Virtual Server 2005 R2 SP1 adds support for the following operating systems as both host and guest environments:
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