I have re-installed windows xp on my computer a few times and I don't know what brand pc you have but I have a Gateway and in the programs there is a driver recovery tool where you can re-install all of them and if I have problems with anything, for example my printer is an HP and everytime I'd system restore I know I always have to go the the device manager and update the HP and its usb and my tigerjet for my magic jack due to an update and compatability issue.
If you find a driver recovery tool and use it, it will automatically pin to your start menu and whenever you seem to lose something, like your audio (all the time) you should be good to go, plus occasionally check the device manager(surprise updates) click hardware and under every catagory just click update driver and you may be surprised at what had an update you weren't aware of, I sure was& just clicking scan for changes hasn't always shown the updates if ever but if there is an update and you clicked update driver then you're set,if no update were available no harm done, it will tell you there are no drivers better than the one you already have installed. I think this is pretty accurate,it works for me I hope it helps.