HD4850 and Onboard Audio Help!

Okay so I have an HP m7250n with onboard Realtek HD Audio and yesterday I installed an Asus HD4850 on it. Now I no longer have sound. I have tried reinstalling the audio drivers from the HP site and uninstalling the HD4850 drivers. I downloaded the video drivers from ATi and only installed the video drivers and still it doesnt work!

Please help!

Go to control panel>audio devices>audio and put back your old sound system.(Sigmatel,Realtek,or w/e)darx55