Almost certainly all sound card manufacturers provide drivers on their websites which you can download for free...
First, what sound card / onboard sound do you have? You need to know the manufacturer and the model first in order to know where and which driver to obtain.
If you don't know what the manufacturer and type is or you don't know how to find out, you can download, install and run Everest Home Edition from: http://www.majorgeeks.com/download.php?det=4181
. It is capable of listing all your system specifications.
Oh...and also, try not to purposely double post...http://www.techist.com/showthread.php?threadid=114463