Everything you need to set up and use VDI for free...

That's what Citrix is providing nowadays with XenDesktop Express. It provides full VDI for up to 10 users, and can work with XenServer, Hyper-V and VMware.

The full link to everything is this one:
http://community.citrix.com/display/ocb/2011/02/04/Virtually%20Everything%20You%20Need%20to%20Set%20Up%20and%20Use%20VDI%20for%20Free