I have a Realtek AC'97 Audio Onboard card and the only problem I have is for example when I play the bismark mission right when the sound plays for the battleship gun shots I get a snap/pop noise right at the begining when it plays, after a while it stops doing it though... kinda anoying and i sent in like 20 e-mails to Realtek explaining the problem to see if it can be fixed in a driver update. I also have the same problem when playing music with Winamp, there is a snap/pop noise at the begining of a song when its played.
Wolfy