|Perhaps a corrupted download? Un-install and try again.|
You may need to enable virtualization. How, I don't know.
System requirements for Windows Virtual PC:
* 1+ GHz processor (32- or 64-bit)
o AMD-V or Intel VT hardware virtualization must be supported and enabled
* 1.25 GB memory required (2 GB recommended)
* Additional 15 GB of hard disk space per virtual Windows environment recommended
A tool for checking whether a PC supports Windows Virtual PC can be downloaded here