Although Windows Server 2003, Datacenter Edition isn't a part of Windows Server 2003 Service Pack 2 (SP2), it's important to mention that its availability has changed. In the past, Windows 2003 Datacenter was available only through OEM partners, meaning you had to buy a system on which Windows 2003 Datacenter was preinstalled. Now, Windows 2003 Datacenter is also available to volume license customers. The different editions of Windows 2003 Datacenter are
- Windows Server 2003 Release 2 (R2), Datacenter Edition (with SP2)
- Windows Server 2003 R2, Datacenter x64 Edition (with SP2)
- Windows Server 2003, Datacenter Edition for Itanium-based Systems (with SP2)
In another big change for Windows 2003 Datacenter that took effect on October 1, 2006, customers can now license an unlimited number of virtualized Windows Server instances. Microsoft's earlier change to Windows Server 2003 R2 Enterprise Edition gave customers a license for up to four virtual Windows Server instances per server. But Windows 2003 Datacenter now allows an unlimited number of virtual Windows Server instances per server and requires no additional licensing fees to run Windows 2003 Datacenter as the guest OS. This change applies to all Windows 2003 Datacenter editions, including the x84, x64, and IA-64 editions, and to Microsoft Virtual Server and VMware Server. For more information on Windows 2003 Datacenter availability and virtualization licensing, go to http://www.microsoft.com/windowsserver2003/evaluation/news/bulletins/datacenterhighavail.mspx.