I don't see XP drivers listed on Kensington's site. If you're going to try drivers for a different card, umm, I wouldn't. A gigabit Ethernet NIC should run you as little as $10.00 to $12.00 depending on how cheap you feel like being.

There are several NICs mentioned in the forums that are documented as working (
see e.g. this thread); I would get one of those.