Soldato
People say they are not audiophiles and just use onboard. Really.. it's only when you go back to onboard sound from something reasonable, you realise how bad onboard actually is in comparison.
A MASSIVE improvement to listening to CD's etc through an X-Fi, and much better in games (not taking CMSS into account, I just mean quality). Even a layman like me can tell the difference and appreciate it )
But if you're not an audiophile you wouldn't 'waste' money on a dedicated sound card anyway, so not an issue!
Also, surely it depends on the headphones/speakers you use? My speakers were cheap, 13 years ago when I bought them!
I think i've got a 5.1 SoundBlaster card in another PC (it came with it) and it's just a bit of a pain really as it has no front panel connectors and I can't say I notice a big difference in audio quality (if any).