It appears there will be a release to manufacturing version of WinXP 64 in March. That's the stage before the CDs get stamped out and the boxes get printed.Read more at The Inquirer
Windows XP 64 might arrive at the end of April

According to some of The Inq's sources close to Microsoft the company plans to launch its Windows XP 64 OS on the 29th of April. By the same time Intel will have finished its 64-bit CPU line.