Why would you want WinXP 64bit anyway, or any 64-bit instance of any OS for that matter?
I just don't understand...Desktop machines are simply not ready for 64bit or maybe I should put it other way around - 64-bit OS'es are not ready for desktop machines.
Mainly because I have 4GB of RAM, plus a 512MB graphics card, and Windows XP 32 bit just can't address it.
I may even opt to use Vista 64 bit instead of XP, but not too sure yet... I still prefer the feel of XP, but can use Vista quite readily too..
Which opens up a new question - why do you need 4GB just yet??? 2GB is enough.