I've seen people run into some issues doing this and one of the guys on our team wrote a good blog post on things you need to do.  Check this out if you are trying to use the VS/VSTS/TFS 2010 CTP under hyper-V: http://blogs.msdn.com/granth/archive/2008/11/03/converting-vs2010-ctp-to-hyper-v.aspx

Brian