Vista - How do I change audio drivers?

I have recently had a windows vista laptop with a sigmatel high definition audio codec. However this codec/driver cannot record audio direct from my sound card, it can only record through noise through the speakers. So I decided to obtain and install the realtek audio driver which I used on my previous windows xp as this can record directly from the computer sound. However I don't know where to put any of the filesso I can select it as default instead of sigmatel. Can anyone help me?