"You are not running on a supported operating system"
Figuring it would be appropriate to try and use as many of the "2008" products as possible, I planned to install Windows Server 2008 and then plonk Visual Studio 2008 and the just-released SQL Server 2008 on top.
I downloaded Virtual PC 2007 SP1 (which was updated to support Server 2008) and then ran the installer.
To my surprise, a dialog appeared saying "You are not running on a supported operating system".
Hang on, I'm running Windows XP with SP3. Double check the system requirements, and yes, it does list XP SP3.
Now I used to run Virtual PC just fine before I reinstalled the OS a few months ago, so what's changed?
Ah ha! I was running Windows XP Professional before, and now I'm just running XP Home - that's what's different! While it doesn't explicitly mention "Professional" on the web page, it is more specific in the installed help file:
Windows Vista™ Business; Windows Vista™ Enterprise; Windows Vista™ Ultimate; Windows Server 2003, Standard Edition; Windows Server 2003, Standard x64 Edition; Windows XP Professional; Windows XP Professional x64 Edition; or Windows XP Tablet PC Edition
But having said that, when they say "not supported", at least they don't appear to mean "doesn't work".