No, but in many cases you can trade in your 32-birt XP license. I can think of  3 possible ways to get hold of XP x64.

1. VL or Volume License Agreement. For users that require five (5) or more software licenses, Microsoft provides volume licenses. Volume licenses can be purchased from an authorized reseller. NOTE: For more information on Microsoft Volume Licenses, visit Microsoft Volume Licensing.

2. System Builder. System builders offer the Windows XP Professional x64 Edition operating system. While System builders are a great way to buy for a reasonable price, most do not help with support and/or missing drivers etc.

3. OEM - Many Original Equipment Manufacturers provide a Technology Exchange Program. If you bought your system from Dell, hp or any other OEM, please check out their websites for an exchange program.