Here is now the offical statement for the supported runtime OS:
- Windows XP with SP2 and later
- Windows Server 2003 with SP1 and later
- Windows Vista RTM an later
- Windows Server 2008 RTM and later
- Windows 7 and later
This restrictions comes from a security desicion to have a hard dependency on EncodePointer, which is only available in the above OSes.
For more info see: Visual Studio 2010: Windows Platforms (CRT)