FIXED - for both users! But you guys aren't gonna like it 'cause I think I got real lucky.

OK, made sure all files were deleted and registry entries gone, right? Do the Device Manager "Scan for hardware changes", but I had C:\WINDOWS\System32 open at the same time. Saw it putting in those @#$% C-Media files again - cmuda.dll, cmirmdrv.exe, cmirmdrv.dll. Deleted them as soon as they appeared. C-Media could not finish installing. Left me with what I needed, the generic "Multimedia Audio Driver" with an exclamation point that I wanted. Immediately ran setup.exe for Realtek AC'97, rebooted, and works great.