Will VDM 2 only support Vista and XP desktops? Or, will it also support Windows Server 2003 Datacenter edition? In a terminal services environment users already have a Windows Server desktop and this isn't a problem, so assuming that you can get around 40 VDI desktops on a two proc box, the per user cost for the OS would less than half the cost of retail XP licenses, and a quarter of the cost of the centralized desktop Vista licensing with SA.