Microsoft Virtual PC

Just to make your life easier from the very beginning if your guest clock is screwed up:
- Check the BIOS option for your Virtual PC and turn off Advanced Power management (VPC Help contains instructions on how to access BIOS).
- Make a change to your .vmc file (it's just an XML). Under the section /integration/microsoft/ add the following text:

<microsoft>
<components>
<host_time_sync>
<enabled type="boolean">true</enabled>
</host_time_sync>
</components>

This should prevent the Virtual PC from attempts to synchronize guest time with the host OS. Just keep in mind that VPC will again re-synchronize with the host OS on reboot unless there is previously saved state for this image.