If you can do some sleuthing to find out exactly what chipset
the wireless controller is, you may be able to find generic drivers.
Start by using Device Manager to obtain the hardware IDs
which look something like this (this is for my gigabit LAN controller):
PCI\VEN_8086&DEV_1502&SUBSYS_1494103C&REV_04
Then plug those numbers into here:
http://www.pcidatabase.com/
In my example, I put the DEVi number, 1502, into the Device field
and it returned:
"Device Id Chip Description Vendor Id Vendor Name
0x1502 Intel 82579LM Gigabit Network Card 0x8086 Intel Corporation"
which I know is correct.
You can then look on the chip manufacturer's website for drivers
which may work.
Alternatively, disable the onboard device in Device Manager and buy
a cheap USB wireless dongle which does have XP drivers available.
HTH
--
Rob