I've checked the settings in control panel, nothing helpful there I'm afraid. The device does not show up in Device Manager at all. Searching for changes in hardware through Device Manager yields nothing.
On the bright side, I tried installing Win7 on another of the machines just in case, and I was able to get the audio drivers straight from Windows Update. Unfortunately, Windows Update on the offending machine doesn't get the drivers. I may be able to dig the driver from a different machine and manually install though?