See if you can figure what chipset it uses via Google -- most adapters use one of a small range of chipset suppliers -- there may be an original driver for that chipset which works with your adapter (though with XP64 your chances are slimmer).
Frankly, I'm seeing current model but used wireless adapters for the less than the price of a Starbucks coffee (okay, cheaper than that) because everyone is buying laptops with wireless onboard. Have a sniff around dealers' bargain baskets and garage sales/flea markets.