I don't know if this changed recently, but when I used to use the X-Fi with BF2 in XP, the framerates actually dropped by half, which was clearly a driver issue. There was a 1000+ post thread on the Creative forums about it. Obviously, many people won't have this problem, but since I did, I never really bothered with it. In Vista, X-Fi has noticeably less advantages to on-board.