I don’t see any reason why NV2 will not be able to run on Windows XP 64 bit. The 64 bit version of XP runs both 64 bit and 32 bit programs. With more memory and processing power on XP 64 bit, NV2 should run as fast as NV1.
Install it and run it. I’d be interested in knowing the results. Send me and email at firstname.lastname@example.org if you have any problems.