Windows XP Professional x64 Edition requires that all system drivers be rewritten as 64-bit drivers, 32-bit drivers will not work. The hardware manufacturers are the ones who need to write new drivers, and they're working on it, but it's a resource issue. Writing and certifying a driver takes time and lots and lots of testing. Resources are always constrained, so the manufacturer needs to make a business decision about which hardware has priority for new drivers. This generally means that the focus is on the newest equipment, and older drivers may take a while, or never be done.