Microsoft has updated its Windows XP 64 bit edition and Windows Server 2003 64 bit editions, and has also renamed Windows XP 64 edition from "Windows XP 64-bit for Extended 64-bit Systems" to "Windows XP Professional x64 Edition." Now that is much better.
Both of these software titles are prerelease, of course, and are available through Microsoft's Customer Preview Program for the XP Professional x64 Edition and for the Server 2003 Edition.
Currently, Windows XP Professional x64 Edition is expected to ship in the first half of 2005, around the same time as Windows Server 2003 SP1. These things were meant to be with us towards the end of this year, however delays with Windows XP SP2 have pushed them into 2005.