I had a similar problem, I have a sound card now, but you have to go to
control panel\Sound and Audio Devices\Audio and select the playback to the sound card rather than the motherboard, you can still leave the
Sound Recording set to motherboard for input, I have the FP HD Audio plug on the X-fi Xtreme Creative sound card and use the motherboard AC97 mic and Aux inputs on the rear of the motherboard, works well.
