Realtek AC97 Driver Windows 98Me2000XP2003.exe

This is the official setup. Drives me crazy trying to find this each time I build or repair a computer, cuz this (along with the proper video driver) seems to be missing most of the time. I got it from download.cnet and extracted it past all that crapware they try to trick you into installing.
This is nothing but the driver setup for audio.
Also worked for me on 2 separate PCs on Windows 7 (32 & 64 bit) by using compatibility mode for XP SP3.
Do a Google search for Compatibility Mode if you don't know about it. It has helped me run all kinds of stuff that wouldn't ordinarily even install.