If I'm not mistakin your sound module (Karajan) is pretty good and much better than onboard.

I have used mostly onboard sound up until about 1 1/2 years ago when I got my X-Fi and sound quality doesen't even compare

Especially gaming!!! The surround channels allow you to pinpoint what direction footsteps are coming from and which direction gunfire is coming from. A perfect example of the benifits of this while gaming is that if someone was sneeking up on you and they made a sound like switching weapons/reloading or walked too quickly you would notice this and turn and fire in the direction of the noise and get the kill almost every time

You should be able to get a small boost in fps also but not a huge one whereas you already have a dedicated card. Hope that helps some