I have the same soundcard on my ASUS board and I ended up putting my old Audigy II in the GF's Dell. The Supreme FX II is pretty slick for movies and music. Not much of a gamer, so can't comment on that.
I believe, and please correct me if I am wrong, I know you will lol, that all of the Asus cards are great sounding but put a small hit on the cpu. If you are borderline on your fps then perhaps the audigy would be better. Don't know about that supreme fx though so yeah.