X-fi Xtreme Audio soundcard problem with 4.1 speakers

[EddiE[uk]]

I recently built a new pc, put the X-Fi Xtreme Audio card in, finally figured out how to get all 4 speakers working, thing is, when I play music through winamp, it's fine, all 4 speakers are working, but when I play a movie in either winamp or windows media player, no sound comes from the rear speakers. Anyone know if I need to change some settings somewhere or shed any light on the matter, much appreciated, thanks