Chances are SC is depriving Aud of memory to play with, or the bandwidth there of. I found similar when playing it with a 1G pc, and this 2G one has over 50% taken up by the game, so therein lay my problem.
I`m finding other things sounding better too now with the extra gig.
If u`r already over a gig, something else is afoot.
EDIT: Did I mention I wasn`t impressed with it either ?! oh. If u find out what the gig is used for in the game, please let me know.