Alright, time to talk desktops. Many of our customers are talking about virtualizing and streaming operating systems to desktops, laptops, blades and even thin clients, so this has quickly become a topic we discuss on a daily basis.

In this post, I'll cover what you need to use something like Citrix Provisioning Server to stream a desktop OS down to a PC, as well as how to license properly for centralized VMs.

Streaming a Desktop Operating System
You need Software Assurance (SA) to do this! So, if you want to use something like Citrix Provisioning server to 'stream' a Windows Vista or XP OS down to blades, desktops etc; the rights to do this exist in Vista Enterprise, which you can only get as a part of Software Assurance. For more information:
http://www.microsoft.com/windows/products/windowsvista/enterprise/benefits/licensing.mspx

Virtualize Desktops, connect via a Windows Desktop
If you have a desktop, laptop, or basically a device that is capable of running a Windows Operating system, you need to purchase VECD (Vista Enterprise Centralized Desktop) for Software Assurance from Microsoft. This is an add-on, per desktop subscription license which is termed the same as your Software Assurance.

If you do not have Software Assurance on your desktops, you no longer need to purchase it (if within 90 days of desktop purchase) and then add VECD for SA. You can now purchase VECD for Thin Clients and use it on PCs that do not have SA.

Virtualize Desktops, connect via a Mac
You can purchase a Windows Vista Volume Upgrade License/SA for your Macs, and then install Windows Vista Enterprise via Apple Bootcamp or VECD for SA to access a centralized desktop VMs. You can even PXE boot your Mac to Citrix Provisioning Server due to the benefits of Software Assurance.

Virtualize Desktops, connect via a Thin Client
If you have a thin device that is unable of running a full Windows desktop operating system, you can purchase VECD for Thin Clients. This is subscription-based as well, and is available via Open Value, Select, Enterprise and Campus/Academic agreements.

That should cover almost every option of licensing Windows desktops for virtualized environments and streaming. Just remember that you can't 'move' your OEM licenses that come with PCs; those live and die with the hardware. You can add Software Assurance to them to get Vista Enterprise, diskless benefits etc, and even subscribe to VECD for SA. However, if you throw away that PC, you lose the OEM license and everything that goes with it. You can 'move' your SA to another OEM PC based on the term left, but that can be pretty complex, so you should talk to your CDW Microsoft Licensing Specialist about that.

Hope this helps.

Nathan