If you've got a BUM map in the old poser 4 format (embossed images in that yucky green colour, if you open them in a paint program), it should be connected to the Gradient Bump channel. That's why P4 and PPP MAT files used in Poser 5 always connect bump maps to the gradient channel. Jpeg bump maps (greyscale images) should be attached to the Bump channel, or can be plugged into the displacement channel in P5. In either case, you don't want a bump strength of 1, which tends to be the default. In Poser 5 that's way too strong. 0.05 works for most things, or even less for close-ups.