Best way to know is to actually try it and see if you like what you hear. If you are not pleased then you should consider adding a sound card.
If you plug it in and it sounds 'good' to you, no sound card needed.
If you plug it in and it sounds 'bad' to you....maybe consider a sound card.
Only your ears can tell.
Yeah I figured that, the headset comes tomorrow just wanted to know if anyone knew if the on board audio for the motherboard is "good" or if it even matters