sound card problem

i am trying to get my GF's onboard souncard to work in her old computer. Its a via motherboard and thats all i know. well i thought I may need to reinstall the driver but the problem is I dont know the exact model of the motherboard. Anyway, I installed my own souncard, a soundblaster pci 32, loaded the (i think) correct drivers etc. Well it is showing up in device manager, but not in the control panels' sound and audio devices, therefore i still have no sound on this computer. When I try to install other drivers that may match it says that the computer cannot find a better match for the driver already installed. Could someone please help me with this?