Gigabyte 965P-DS3 Mobo and Sound

[Riiya]

Hi. I've got a Gigabyte 965P-DS3 Mobo and a Creative Xfi soundcard; however, I cannot seem to find the option to turn off the onboard sound so I can use the creative soundcard.

Everytime I install the creative drivers, It reboots but then the onboard sound takes over.

Any ideas?

Thanks!
Brian.