Help, please!
I have IBM Think center 50.. or whateever, with the same AC'79 audio.
I've tried all you said but still - "driver not found, reboot and...".
But! After installing Realtek AC'97 - there appears audio parts, that was before just like one "unknown" audio. But still there is no driver on "multimedia audio controller". I've tried an "driver update". It now, after installing Realtek codecs or whatever - found something, but in some time when installing wants "Realtek disc" or just some .sys file.