Desktop Virtualisation: Options and Licensing
As the trend for hardware consolidation and virtualisation increases, so do the queries across the licensing desk. Here is a brief breakdown on the common Desktop virtualising options.
What do you get with your Desktop Windows 7 Licence?
When purchasing Windows 7 only, without Software Assurance, you get one Physical licence and XP mode to run virtually on the machine. 
Should you wish to run more than Windows Licence on the machine, you will need to purchase Windows
7 Enterprise and have Active Software Assurance, you can run up to 4 virtual instances of the software in virtual machines per licenced device. You may create and store an unlimited number of copies for use on any licenced device. You can downgrade to previous versions of the Windows Desktop operating system in the virtual instances should you wish
Remote Desktop Services
By Licensing each user/device with a Windows and Remote Desktop Services CAL and an application (for example Office) through Volume licensing (only the Application needs to be through Volume Licensing), the customer can run the application from the server. This is limited in that multiple users access one OS or Application, hence the OS/Application is shared. No single user can reboot the OS of the shared users. If you would like this control, you would need Licence correctly for each user to have a full desktop running in the virtual environment.
Running Virtual Desktops from the server
VDA is now an SA benefit when purchasing Windows 7, therefore, if you have a desktop covered by SA and you want to access the Virtual Desktop Infrastructure environment, you can do so without purchasing any additional licensing. Any Device not covered by SA or any non Windows Terminals require the VDA licence in order to access the VDI
VDA Licences
If the customer is not covered by Active SA on their Windows 7 Pro licence, they can get the VDA Licence through the Open Value program as a monthly subscription. This will allow you to run a Windows 7 Desktop on the server and access this remotely. This licence is suitable for those devices which do not qualify for SA. So thin Clients and even contractor or employee owned PCs can be covered by the VDA Licence. With the emergence of tablets into the work place as well, those customer looking to run Windows 7 on iPads can licence them in this way too. VDA includes all Client OS Software Assurance benefits.
VDA is licenced PER DEVICE but if the device has a primary user, then this user will have roaming rights to access their desktop via other devices such as home PCs, hotel PCs etc. If the device has multiple users, then this right does not apply.
FPP in VDI Scenarios
An FPP was designed for desktop deployment of the operating system. It is not the ideal licence for running in a VDI environment and has many restrictions. For this and other VDA information, you can download more information from:Licensing Windows for Virtual Desktops – Microsoft
