How do you uninstall the old drivers? And how would I check that the on-board sound hasn't been disabled?
You can uninstall them through Add/Remove Programs in the Control Panel, or more thoroughly with a program like Driver Cleaner.
I was talking about it being disabled in the bios, but don't worry about it, if it wasn't a problem before, then it shouldn't be a problem now. It's just something that I've turned on and off and sometimes forget about on my system.
How would I check that it was different? The tooltip for the icon in the system tray indicates that the device is "Realtek AC'97".
I went to the Realtek site to get the most recent drivers, then to the Intel site (for reasons I don't remember) to get a SoundMAX driver. I installed the Realtek driver first (without uninstalling whatever drivers I currently had), which didn't work, so then I attempted to install the SoundMAX drivers, which didn't work (for reasons I don't remember). I've been away for the last three days, so I haven't done anything else. Thanks for your help so far.
But were your drivers for your specific motherboard? Have you tried the original drivers on your motherboard's CD? If you need your motherboard model, it should be written in the largest lettering near the center of the board.