Honestly, there's so much hype these days over nForce's integrated audio and how good it is, how it can blow everything else out of the water (especially Creative sound cards because people want to avoid Creative and want to believe at all costs that nForce audio is their savior), etc. that people have started to believe that the Soundstorm is the best solution available period. But that's not the case and will never be.
First of all the normal nForce integrated audio (i.e. no APU, no digital output, including Soundstorm boards connected to speakers/receivers/etc. via analog ports) is just as good or as bad as the CoDec chip on your mainboard. Almost all nForce2 boards come with RealTek ALC650 Codec chips which is quite honestly a shitty digital to analog (and vice versa) converter and NOWHERE even remotely close to the quality of PCI solutions like TBSC, Fortissimo3 or Audigy. Audio processing tasks like applying 3D effects all rely upon the system CPU and you get NOTHING better than ordinary onboard audio that is on every other intel/AMD mainboard today.
If we're talking about Soundstorm certified mainboards (i.e. integrated APU which provides ample processign power for 3D audio effects and calculations and also the much-hyped real-time Dolby Digital encoding AND a digital output) things get much better. Games may run even faster than when you have a Creative Audigy card (although the differemce is not at all discernable by the user plus the fact that EAX AdvancedHD 3 and 4 effects are only available through the Audigy/2/2ZS line of cards). If you use the digital output (notice the 'if') you can enable the DD 5.1 encoding to get 5.1 sound from any audio source that can provide it e.g. 3D games without all the hassle of connecting the analog ports of your setup to your speakers, receiver, etc. There's another big benefit to this i.e. you're skipping that evil onboard Codec chip and will be getting way better quality with the one inside your digital speakers or receiver. Which gets me to my final point: If you don't have a speaker setup or a receiver with a digital input, you're back to analog and that means again using the onboard shitty converters like the ALC650 and the sound quality will be just like any other onboard sound out there. Remember that there's so much EMI going on inside the computer case and on your mainboard that even if you use a very high-quality DAC chip onboard, you won't get high-quality sound. That's exactly why high-end sound cards for the pro users come with external boxes that house the converter chips. They keep the chips out of the reach of the noisy PC environment to get decent quality.
So, there you go. If you're not concerned about the audio quality, nForce is just like any other onboard audio solution. The single benefit of Soundstorm certified boards is real-time DD5.1 encoding BUT that's only accessible when using digital output.
BTW as a final note, Turtle Beach Santa Cruz is considered by many to be the BEST sounding consumer solution of its time (even right until now, its main competitor of course being the original Audigy not the newer 24-bit cards). And you can be sure its performance will be just on par with the nForce APU for games. So, I think you better put it back where it was and enjoy that clear crisp sound again! The difference in quality will be quite noticable.