for linux sound support, people prefer to use alsa instead of the modules in the kernel code. u can try to check http://www.alsa-project.org/ to see if u can install that.
if i am not wrong, ac97 is a sound standard, not a sound chip, u should know which chip u use. basically, u can boot with u old kernel again and use lsmod to see which module it loads. then u know which module u need have.