I have recently purchased a Dell 5150c with a Sigamatel sound card installed.With the pc i recieved a pair of stereo speakers but changed these to 5.1 creative speakers.But these only have output on the front two speakers and the woofer.I have emailed Creative  who say that the speakers do not need drivers to work but should work with my sound card.Dell support have told me that my system should play 7.1 so there is no reason why these speakers should not work.When i open my volume controls the advanced options are not highlighted which i reckon this is where i enable 5.1,i have already have all other controls enabled for 5.1please help

Alan