Microsoft published a video about installing a complete MS VDI solution and how many servers does it take.  Video showcases that you can setup a complete solution including backend, broker, and web publishing to provide virtualized clients on a single physical Windows Server 2008 R2 box.  This sample uses Windows 7 for the guest.     The complete 16 minute video is at http://www.microsoft.com/showcase/en/us/details/fbaf6f70-45fd-4c81-be70-6d276d54776b

To learn more about Microsoft VDI:

http://technet.microsoft.com/en-us/library/dd647502(WS.10).aspx (step-by-step guides)

http://social.technet.microsoft.com/Profile/en-US/?user=RemoteDesktopServices&sp=tng (scripts)