The biggest issue with embedded sound cards is their tendency to lose audio sync -- be it audio drift, or simple butchering of the signal. The clocks are not always stable, hence the suggestions for dedicated sound cards from better companies like Creative (SoundBlaster) or Turtle Beach.
Poor shielding from soundcards also lends itself to adding weird noises into your audio playback and recording -- little beeps, buzzes, helicopter sounds, etc.
I honestly don't even waste my time trying onboard audio anymore, if the machine is meant to edit audio or capture/record audio or video. It's a good $25 investment to just get a decent card. The only time I'll use onboard audio is if the system is a encoding box or non-editor (web design system, for example).
For example, at only $30: http://www.amazon.com/gp/product/B00...SIN=B000LP0R3E
I'd buy that, if I wanted another sound card.