Sound cards changing positions

Hi, I installed three sound cards in an XP PC and the new Multiplay cue system is working great. The setup is this:- Three pci sound cards. (1) Aureal (2) Sound Blaster Live (3) Sound Blaster wave Multiplay (or me) allocates Output one to card one, output 2 to card 2 etc. The outputs are then wired through the mixer board to particular theatre areas. All is fine and works a treat. The problem is this:- After each PC start up, Windows allocates each sound card to a different position, so:- (1) becomes Sound Blaster wave (2) becomes Aureal (3) becomes Sound Blaster Live (at random). For no apparent reason the sound which should be backstage suddenly comes from front of house. This is not insurmountable of course. All I need to do is re-set them in the software after every startup. It just makes it complicated for a novice operator to cope with. Is there a way you know of to permanently fix their position within windows? Opening night tonight and apprehensive!!! Thanks frostyboy