Well, I'll give you an A for effort!
This usually doesn't work as well as you have described, but nonetheless let's move on. The unimodem device is probably voice/fax modem that was in his machine. If there is a modem there, you will need to get the drivers for it, or anything else hardware based that was not automatically picked up. You can remove the modem and look on it for information, an FCC ID#, etc, or you might get lucky with it and all the other unidentified's by downloading and running Everest Home Edition, free at www. lavalys.com. Once you know what you are looking for we can get the drivers.
He may have a sound card in there but it would probably be listed as a PCI multimedia Device, or something similar.
If you had sound on yours (what model is it?) it would probably be built in to the motherboard, and so, not transferrable.
He may or may not have sound on his. What make and model again?
Are there any other yellow marks in device manager?
Let us know.