Most of the time drivers meant for Win 2000 will work fine in Win XP, if there are none listed for XP. There was no XP when your card was made. Win 2000 and XP are both derived from the same Win NT predecessor.
I used Win 2000 drivers for my CT4750 and they work fine in XP. The ones XP auto installed do not work with it - they are for the other "family" of cards.
"Its a Gateway 700x with a Lexington 850 Mother B."
I found no Gateway 700x anything using a simple search on the Gateway web site. I found a 710X, but it does not use one of the Lexington mboards.
There is a sticker on your case with a more specific model number - 2xxxxxx or 1xxxxxx
.
there are three Lexington mboards - Lexington, Lexington 2, Lexington 3
All three have a BIOS maintenance mode that allows showing (a) screen(s) in the bios Setup you don't normally see.
General guide here:
http://support.gateway.com/s/MOTHERBD/INTEL/2517944/2517944ul.shtml
Maintenance mode jumper position shown here:
http://support.gateway.com/s/MOTHERBD/INTEL/2515762/2515762mvr19.shtml
That and other Hardware Details here (Lexington 2):
http://support.gateway.com/s/MOTHERBD/INTEL/2517944/2517944tc.shtml
Lexington and Lexington 3 mboards have no mention of onboard audio.
Lexington 2 mboard - DOES have onboard audio:
The motherboard includes an Audio Codec '97 (AC '97) compatible audio subsystem consisting of:
Intel 82801BA I/O Controller Hub (ICH2)
Analog Devices AD 1885 analog codec
Assuming your mboard is using a 2.0ghz cpu, it is one of the Lexington mboards listed here - the 251xxxx number is probably on a label on the mboard:
http://support.gateway.com/support/supinfo/index.asp?pg=2&file=dt_mot063.html
If your mboard is not using a 2.0ghz cpu, choose the cpu speed here, then find which Lexington mboard you have by the 251xxxx number:
http://support.gateway.com/support/supinfo/index.asp?pg=2&file=dt_mot003.html
If you DO have a Lexington 2, you DO have onboard sound, whether or not there are 1/8" jacks for it, and you must disable it. If you see nothing about that in your normal bios Setup screens, move the jumper to Maintenace mode position (move it when the computer is UNPLUGGED) and see if the sound can be disabled in the screen(s) enabled by that mode in the Setup.