The number you'll be looking for should start with CS and then a 4 digit number. Possibly beginning with 42XX. XX being the upgraded version number. If it's onboard then you'll need to look for the onboard sound chip. It should also have a model number printed on it. If your using a notebook or E machine it'd help in finding what you need. I've got a site with about 200 different drivers for Windows 98 Crystal Semiconductor drivers.
This would help even more to find what you need. If it's a major company built computer (ie: Gateway, Dell, ect...) then let me know the model of the computer. If it's not and it's a home built then I'm gonna need 2, possibly three things. The motherboards company and model number. This is normally stamped in fairly large letters/numbers on the board. If it's an onboard audio which I don't think it is if it's asking to install a PCI Management bus driver. I'm going to need the model number stamped on the onboard audio chip. If it's a PCI then I'll need the number stamped on that board, possibly starting with CS. If you can find the number on the PCI board then that will make it much easier to find your driver. If you can get me atleast one of these three things I should be able to get you the correct drivers.
I don't want to find any driver and have you try it. These items that I've stated above would help me out tremendously with getting you the proper driver files. Just shoot me an email or post here with the info you can find and I'll do what I can to help you out. I know how frustrating it is to not have the drivers you need. I've been there before and practically ripped my hair out trying to find the right files.