Sound became choppy/distorted after upgrading from vista to win7?

Hi! so i installed windows 7 ultimate, before, when im still running vista, im using Realtek High Definition Audio Manager and it works just fine, but after installing win7, all sound coming from my speakers are distorted (every time while playing music, mp3's, videos. even games) what should i do? btw, im using only the typical stereo speakers. my soundcard is built-in. my pc is acer aspire m1610.