Poser Pro Pack & Poser 5 use "jpg" bump maps, while Poser 4 uses "bum" bump maps. This can make a huge difference to you. Some products use MAT Pose files that include versions for P5/PPP, and for Poser 4 (P4). You really want to go over your stuff and see what's what. You can save lots of disk space by avoiding the BUM bump maps! That's why I don't use the P4 runtime in Poser 5.