Not so long ago, Windows XP and Windows Server 2003 for x64 were released to manufacturing (RTM’d). Today, they have finally shipped and are available to consumers, but you won’t find these yet on retail sales shelves.
Windows XP Professional x64 Edition is available on x64 machines now, and users with x64 machines now can exchange their 32-bit Windows XP for the x64 edition. You may also obtain this through the Microsoft Product Information Center or our Volume Licensing program for 5 or more computers. If you’re a developing thinking about or already planning on targeting XP x64 be sure to check out the Windows XP Professional x64 Edition community portal.
Windows Server 2003 x64 Editions are also available on x64 machines now, but you may purchase them through Microsoft and registered resellers. You may also visit the Windows Server 2003 community portal.
Make sure that before you upgrade you check driver availability for components in your system. My x64 development and test machine for testing the x64 install and patching of the .NET Framework didn’t have drivers available for the integrated NIC but we had nother NIC with drivers available that I installed.