The release of Windows Server 2003 x64 Edition and the Windows XP Professional x64 Editions is expected in the first half of 2005. Microsoft’s 64-bit support for the x64 architecture can't come any too soon; virtually all the mainstream hardware vendors already have 64-bit offerings. The only real holdup is the lack of the native 64-bit device drivers that are required to run the 64-bit versions of the Windows OS. Because porting the 32-bit drivers to 64-bit systems is a relatively trivial task, however, Microsoft should be able to provide those missing components soon after releasing the x64 versions of Windows.

Microsoft currently plans to release the following x64 editions:

  • Windows XP Professional x64 Edition
  • Windows Server 2003 Standard Edition
  • Windows Server 2003 Enterprise Edition
  • Windows Server 2003 Datacenter Edition

Notably, Microsoft has no plans for an x64 Windows 2003 Web Edition.

The new Windows 2003 x64 Editions will incorporate the Windows 2003 Service Pack 1 (SP1) updates. In addition to patches, rollups, and other OS updates, the Windows 2003 x64 Editions will include SP1 features such as Windows Firewall, Post-Setup Security Updates (PSSU) support, and the Security Configuration Wizard (SCW).

The 64-bit architecture improves server scalability by eliminating the 4GB memory barrier that's inherent in the 32-bit architecture while maintaining the familiar Windows interface and management tools. Microsoft's initial testing determined that the Windows 2003 x64 Editions have some significant performance advantages over the 32-bit version of Windows Server for several specific workloads. Table A lists some of the workloads and the performance gains that Microsoft’s initial testing indicated.

To ensure a good customer experience, the x64 editions of Windows Server and XP will be available only through Microsoft's OEM partners, who will make sure that the systems they sell have 64-bit driver support. At the time of this writing, Microsoft didn't have any plans to release retail versions of the Windows 2003 x64 and XP x64 OSs.