I downloaded the recently release Windows 8 Developer Preview and was trying to work out which system to load it on when i found this article.
How to Boot from VHD with Windows 8 Developer Preview.
All the steps seems to work OK for me, but then Windows 8 didn’t want to install. Not sure, but several people in the comments section on the site says they got it working. And it did boot into win8 OK, it just didnt want to install.
Update : I haven’t been able to get this to work, but some people in the comments section at the link say they have. Best of luck if you want to try it yourself. 