Peggy, I have PZ3's going back to poser4 stored on a 3rd Internal HD & have had NO issues.  Just installed poser 7 &  no real need for Poser 6 IMO.  I just copied my RT's over to P7's RT.  PZ3's weren't even in even the transfer scheme.  In fact my PZ3's are on the same Drive as Vue ;).  Easier that way!