If I am using my motherboard sound, I want to install a sb audigy zs. Do I need to uninstall the drivers for the onboard sound or can I just install the board and use the board
Depends how careful you want to be. I've installed it over my onboard and had no problems, but nobody recommends it. It depends on how easy it is to install and reinstall your onboard sound and whether you plan on using it: if you don't plan on using the onboard anymore, you might as well uninstall it: taking up harddrive space. If it's a snap to reinstall, you might as well uninstall, install the audigy, and then reinstall the drivers: it's safer. If it's a pain to reinstall, just install the audigy over it and hope that nothing happens.