Incompatible Driver For Sound Card?

I got a second hand computer with a mother board good enough to run windows 7. The sound card (do you still call it a sound card if it is on the motherboard?) gives out a very faint distorted sound. I thought this was a duff sound card so accepted it.Recently I got a window telling me the sound card wasn't set up properly, did I want it set up ? I pressed FIx and after a short while got a box up saying there was no driver for this card on windows 7.Is there any way I can get round this and perhaps use a driver for another version of windows?I have tried various helps including Microsoft and been told to click on the driver I have put on the desktop and do various things with it (or something like that, I can't find the window again) I havn't got a driver ?I can't afford another computer.I managed to download a piece of software advised elsewhere on this site and got the info that the sound card is realtek ac'97 for via(r) is this a type of sound card?

update II I managed to download and run a driver from an internet site (download cnet) for the realtek ac97 for windows 7 but it has made no difference. I have restarted the computer but the sound from the speakers is the same. Could it still be a software problem or do I have a hardware problem with the sound output?