Drekinn and sswift, youre not using voodo banshee based cards are you?
those cards couldnt do more than 16bit colour in fullscreen 3d. or rather any 3dfx card could not do more than 16 bit colour in fullscreen 3d and often could not do 3d in windowed mode at all (so if you have one of these cards and are getting 3d in windowed mode with 32 bit colour its likely you are not using hardware acceleration any more)
those cards couldnt do more than 16bit colour in fullscreen 3d. or rather any 3dfx card could not do more than 16 bit colour in fullscreen 3d and often could not do 3d in windowed mode at all (so if you have one of these cards and are getting 3d in windowed mode with 32 bit colour its likely you are not using hardware acceleration any more)