To IsaoShi: The method you have suggested was what I was trying to use; however windows did not give me any option for opening with poser.

To Fylbrigge: I finally installed P7 SR3 over the top of the one I had copied to the external drive, then it was able to "see" P7 as an option for opening the pz3 files. I also installed P7 to the main computer drive. I had hoped that I could have all my poser stuff on my wallet sized, USB powered 500GB external and easily move it from one computer to another without installing P7 on each computer but that may not be possible.Thanks for your help!
Lance