Microsoft Windows Vista Enterprise Centralized Desktops (VECD) is a unique way to licence Windows OS on virtual machines (VM’s) as part of Virtual Desktop Infrastructure (VDI).
The desktop OS (Operating System) images are held on a server and users access them via PC or Thin Clients*. You can have an unlimited number of OS instances on the server, these can be Vista or downgraded to XP, it is licensed by Device and you can have 4 virtual instances per access device at a time.
VECD is priced on a per device per month basis (so 100 users = 1200 units x price) for a minimum of 1 year.
A link to the Microsoft page which includes various datasheets can be found here.
Running Virtual Instances on the desktop is becoming more and more common and, of course, poses it’s own problems when it comes to licensing. You must have a separate OS licence for each VM as well as the OS licence for the physical machine.
If VECD isn’t an option for whatever reason, you can run OEM (Original Equipment Manufacturer)/FPP (Full Packaged Product) inside the VM to give you the OS licences. However if your corporate standard is still XP (as it is with many companies) it gets a bit trickier! You won’t find an OEM or FPP copy of XP now so you will have to start with Vista and downgrade to XP:
1) Buy a volume licence for Vista= NO. The Desktop OS volume licence is UPGRADE ONLY and as a VM is a clean machine, yo’re not eligible to install an upgrade.
2) Buy an OEM Vista licence= NO. Although OEM licences of Vista Business/Ultimate give downgrade rights, you’re not eligible for OEM licensing as they’re not being installed on a “new” physical machine.
3) Buy an FPP copy of Vista and enrol it in to Software Assurance (SA)= YES. Enrolling an FPP licence into SA** grants you Downgrade Rights, so you can take Vista down to XP and it’s a full copy so you can install it in a new clean VM.
* PC’s MUST be covered with Software Assurance (SA) to be eligible for VECD.
**You have a time limit to enrol the FPP copies into SA. 90 days for Open Licensing, 30 days for Open Value/Select/Enterprise Agreements.