It's all in the eye of the beholder...
For starter, when it comes to sound, and in the context of a PC, we only thought about how much it's gonna relieve the CPU for the sake of a few extra FPS, positioning like from 5.1 to a ridiculous 7.1, EAX 2.0 for the non-Creative and EAX4 HD for the X-Fi clan...
Who cares about the quality? I do...
In fact, I never bother to buy any Creative soundcard since I bought a 'generic' one; a Hercules Gamesurround Fortissimo III 7.1 that uses 2 CRYSTAL Sound Chip... If u ask me how good it is, better than onboard audio AC97, slightly better than a Live! in certain areas. Price? RM250.
Somehow, how good the quality of sound in a PC would go? The level of audiophile quality? It'll never reach that stage and by saying it would, we would only draw flamethrowers by those who've invested a gazillion ringgit on audiophile equipment.
Frankly, I'm no soundcard enthusiast but I'll never took a glance at all on the onboard sound because it's simply crappy. I've tried my ears on Azalia, nothing impressive. If I'm to plug a big can over it, there aren't even enough juice to drive it, but a soundcard might stand a better chance. Personally, I favour ENVY24HT chip by VIA. But then again, I've just read a review on a new HD Audio card with the soundchip came from an unfamous company

released by 2 company, one is designed in Korea, another is in USA.
No matter what, I believe I would continue to stick with the purchase of PCI soundcard or PCI-E if they finally wished to release one. And the next target would be ONKYO WAVIO SE-200PCI !!!!