Well, in response, it depends on what you are going to be using it for. It will offer better quality in sound, but if you don't consider yourself an audiophile, it may not make a difference. Furthermore, a sound card does increase the framerates in games, because the sound card takes the brunt of processing hte audio, however, this is very SLIGHT, i may add.
I personally have a 5.1 audio setup and my mobo supports 5.1, so i stick w/ that and DON'T have a soundcard, and im perfectly ahppy. hope that helps
ANd if you don't mind, partly out of curiousity, what speakers did you get???