CMSS I have found reduces fidelity in the sound quality and on researching the net, it is true. Dolby ProLogic II is much better at upmixing.
As for a good soundcard, the creative soundcards don't stand a chance when compared with an Auzentech X-Meridian or even its lower counterparts.
A good soundcard:
- produces high signal to noise ratio
- improves low quality mp3 files (X-Fi crystalizer, Auzentech has something of their own)
- Reduces CPU usage
- Decodes DD and DTS signals much better than a software decoder
- provides for EAX sound effects in games..(5.1, 7.1)
- Has the power to output/input sound at high resolutions (192Khz/24bit)
You will NOT feel the difference in a blind test on an average speaker system as onboard soundcards have grown quite a bit. But plug in something good, and yes, I can tell the difference.