Depends really what you want the card to do. If you want the card for audio playback/gaming/movies ect ect then onboard sound is or one of the mainstream sound cards will work OK. As a recording or reference audio card, they won't cut it.... convertors and s/n ratio just aren't designed for it.
What software did you use to record and do you watch the meters and check for digital clipping when recording/mixing and mastering?