A: With the release of Windows Server 2012, it's no longer possible to purchase earlier versions of Windows Server. However, the Windows Server 2012 license has downgrade and down-edition rights (whether it is covered by Software Assurance or not). Microsoft's Product Use Rights document covers the downgrade rights (see pages 28 and 29). Essentially, the following applies:
  • Windows Server 2012 Datacenter - Can run any earlier version of Windows Server Datacenter in addition to being able to run Standard or Enterprise in the virtual instances associated with the Datacenter license
  • Windows Server 2012 Standard - Can run any earlier version of Windows Server Standard or Enterprise edition (since it's no longer possible to buy Enterprise edition)

Using the downgrade or down-edition rights doesn't mean you can't use the license for Windows Server 2012 on the hardware.