I'm not sure that AC97 DOS drivers exist at all. That should be checked on realtek's site. However, I do have a potentially better solution for you called VDMSound. Its basically a Win9x/WinXP based DOS driver for soundcards. You can run games from Windows, and the sound will (probably) work flawlessly
here's the link
http://www.ece.mcgill.ca/~vromas/vdmsound/
Hope things work out! Cheers!