I had no end of snags getting an AC97 chip going. But eventually managed to sus it out, though since then I have changed it and now have a soundblaster live! 5.1 stuffed in a pci slot.
Anyway, have you tried searching for AC97??? the damn things get lotsa mentions.
The threads that they are mentioned in, often start with "have you tried opening a mixer - aumix, kmix or something like that?" because they are often "muted" by default during install.
Sorry, it isn't much, but at least it's a start!