Speaking of performance, Hyper-V R2 performance is really good - Microsoft saying "Hyper-V is exceptional". 

 

Microsoft recently released an in depth performance analysis on Windows Server 2008 Hyper-V R2 Virtual Hard Disk Performance using a variety of workloads including SQL, Exchange, Web and more.

 

This is a must to read: http://download.microsoft.com/download/0/7/7/0778C0BB-5281-4390-92CD-EC138A18F2F9/WS08_R2_VHD_Performance_WhitePaper.docx)