I have just had this issue with my lap top (exactly)
the driver you downloaded is a self extracting package not an installer. So you need to go to your device manager, [Control Panel->System->Hardware->Device Manager] Right click on your "Multimedia Audio Controller" with the yellow exclamation mark, and go down to "Update Driver" a Hard Ware Wizard will open, check the box that says "Install from a list or specific location (advanced)" click next. Make sure you check the box that says "Include this location in the search:" and the driver should be located here "C:\DRIVERS\WIN\AUDIO\SMAXWDM\W2K_XP" if you extracted the package per it's default extraction location. Click next and then finish... it should now find the driver and install it.
Hope this helps
