DirectSound would probably be my 'preferred driver' on Vista, and it seems to work for most people.
You wouldn't need updated drivers for Vista, since DirectSound is now entirely software driven (ie. no hardware acceleration). From what I understand, this means that if you have sound in Vista, you will have sound for any game that uses non-hardware features (DSP, Positional Audio, etc.) of DirectSound. I doesn't help that I have no clue about the PC specs, does it? :/
You can use something like System Info for Windows to get information on pretty much everything you need to know about someone system (and quite a bit you probably didn't want to know).