They have XP for 64-bit??
There is a 64-bit version but it wasn’t widely used.
The primary benefit of moving to 64-bit is the increase in the maximum allocatable system memory (RAM). Windows XP 32-bit is limited to a total of 4 gigabytes. Windows XP Professional x64 Edition can support much more memory; although the theoretical memory limit of a 64-bit computer is about 16 exabytes (16 billion Gigabytes), Windows XP x64 is limited to 128 GB of physical memory and 16 terabytes of virtual memory.
Windows XP Professional x64 Edition is in fact an edition of Windows Server 2003. Both Windows Server 2003 x64 and Windows XP Professional x64 Edition use identical kernels and are built based on the same code bases.[2] Although based on the Windows Server 2003 code base, Windows XP Professional x64 Edition does include client features of 32-bit Windows XP such as System Restore, Windows Messenger, Fast User Switching, Welcome Screen, Security Center, Games, etc. which Windows Server 2003 does not have.
Windows XP Professional x64 Edition is not to be confused with Windows XP 64-bit Edition, as the latter was designed for Intel Itanium processors.[3][4] During the initial development phases, Windows XP Professional x64 Edition was named Windows XP 64-Bit Edition for 64-Bit Extended Systems.[5]
http://en.wikipedia.org/wiki/Windows_XP_Professional_x64_Edition