Apparently it will still work on Windows XP Home. It will just give you an error saying the OS Isn't supported, you should be able to ignore it and continue.
Cool. You sure wouldn't know what to make of all the supposed Vista problems looking at these reviews-
Customer Reviews Of Microsoft Windows Vista Ultimate SP1 64-bit for System Builders - OEM
It sounds like it's mostly just a lack of 64 bit software support as of yet.