XP64 is not supported, the only 64 bit OS officially supported are Vista and Windows 7. Unofficially, we can say Windows 8 works, but none of use ever get the chance to test XP64 so, you are really on your own.
In addition to the published system requirements, which don't include XP64, that's why we have a Trial version for, so you can't risk buying something that might not work on your system.
I strongly suggest you to upgrade to a more recent OS, XP64 is no longer supported by Microsoft since April this year, and you'll going to have more and more problems with 3rd party software and drivers in the future.
