You don't have any choice in the matter. Just boot into Win7 64-bit & install the correct Win7 64-bit drivers, then boot into XP & install the correct XP 32-bit drivers there.
Both sets of drivers will be kept separate & loaded separately so there's no way one set can interfere with the other operating system.
Both sets of drivers will be kept separate & loaded separately so there's no way one set can interfere with the other operating system.