If you don't have fantastic speakers/really fantastic headphones, it's not worth getting a sound card. Do you have a setup that would make this worth it?
That would take some pretty serious cash, at least several hundred in speakers. Otherwise, it's not really worth it.
If you're looking for surround sound, again, if you're not gonna drop a ton of cash on an extra-fancy setup, get a cheap card that can handle 5.1 sound.