Sound Driver Problem

The driver on the MB may be disabled in BIOS setup,you should reference the notherboard manual to locate the on board sound,you can then enable it

If you have a pci sound card installed then you may have a conflict to which you need to disable the onboard sound card,then locate the manufacturers web site for the sound card and download the drivers for Windows XP

Find the chipset for your sound card, (like a model number on the chips themselves) and go to the manufacturers site to see if they have drivers for windows xp.

I need more info on the motherboard to help you but maybe this will point you in the right direction.

http://www.kobian.com/download_product.php?category_id=76&product_id=207
Hope this helps!