Auguste: You used to hear about the great new sound cards all the time 15-20+ years ago, but not any more. Is there any real benefit in shelling out the extra money for a proper sound card these days, as opposed to using integrated cards? What exactly do they offer that integrated cards don't?
I picked up a used X-Fi Music card from PC World about 3 years ago for £25, and it has proven to be one of my best tech purchases. The quality of the sound versus onboard is especially noticeable when playing a CD in Foobar with bit-matched sound, to the extent that it is actually shocking what a poor audio solution masks on a track.
Games are also much more atmospheric, even these days with Microsoft changing the audio architecture in Vista and 7. The only downside, as mentioned above by others, is that driver releases are nowhere near as prolific as for my other hardware components.