As there are many versions of the Realtek
AC97 driver and codecs, could you give moe specific details?
Go to Start > Run, and type msinfo32. then expand the Components tree and choose a device
Go to Control Panel > Device Manager and look for any entry that has a yellow flag beside it.
The chipset info is really what we need
an example:
This
driver supports all ALC series audio
chipsets from ALC101 up to ALC861. It is used as onboard sound on many motherboards.
Chips covered include ALC101/201/202/203/250/650/653/655/658/861