The simple answer is MS Virtual PC doesn't support x64 clients never has done, Try VirtualBox. Virtualbox works but was iffy last I tried VirtualBox-3.1.4-57640-Win, Vmware workstation works excellent with 64 Edit: iffy with usb jumpdrives but may have improved by now and VirtualBox is free I use VMware Server under XP x64 but have no experience yet with W7. The VMware forum indicates that a W7 guest can be run as Vista VM (i.e, select Vista (32 or 64) as OS when configuring a VM). I also have seen people there talking about installing VMware Server in a W7 host. The real advantage to VMware Server is that it is free. Enjoy, John. thank you for tip. i got it vmware to work, now i can test images i make without doing a real install!!! which is what i was doing