Unless your system is a real dinosaur, the onboard sound chipset should be more than enough for even hard core music listening. Many of the newer systems have onboard sound that can support up to 5.1, 6.1 and even 7.1 speaker systems. In some cases, installed a dedicated sound card can actually cause your game/sim performance to suffer as the MOBO and CPU have to spend extra energy and processes directing the sound to the sound card and powering the card. My advice, if what you hear coming from your speakers is good enough...don't fix what is broken. Just take the time to make sure that the driver for the sound chipset is up-to-date...I updated the driver to my onboard chipset and an annoying crackle instantly vanished and the quality of sound improved across the board...and I had an updated sound configuration utility with much more flexability and tuning.
OBIO