You have to watch out for these people who are clearly not audiophiles, saying that soundstorm is actually better than an audigy. The audigy has excellent analog output. I can't hear any noise from it. However, the soundstorm can output full surround digital, which almost nothing (including audigies) can do. The soundstorm is awful for analog applications. The audigy is the best I have heard. A lot of the "crackling" some hear is the noise from the Soundstorm's DACs! You simply cannot say that the soundstorm is superior in sound quality to an audigy. If you listen to them on headphones, the truth is revealed. I can hear noise from the Soundstorm when I move my mouse! Um, cujo, the sound tests in 3dm2k3 are not quality tests, they are performance tests... If you want to get into sound "tests", get foobar 2000. The audigy will output insane bandwidth and frequencies, while the soundstorm can only do what my mom's hp pavilion laptop can do.
As for overclocking, if the the PCI bus is locked, there will be no difference.
unwrittenLaw, if you have the cash, go for a Audigy (either one is excellent). They are far superior in analog sound, so with your analog speakers (and headphones especially, if you use them) the sound quality is the best. You can even get the kX drivers (free) for the creative cards if you dislike creative's drivers.
I am a full fledged audiophile (as in, "my 'crappy' headphones cost $150"), and I say the audigy owns the soundstorms. They are both fast, and the Soundstorm is excellent for onboard sound, but it cannot stand up to Audigies and even some TB SCs. Crap, i even prefer my Aureal Vortex I. I have an audigy and the Abit, and i used to have the Asus, both soundstorms worked perfectly, neither was anywhere near the audigy. Any questions, unwrittenLaw, feel free to pm me.