Yes, You can point Poser 5 to your Poser 4 library. I zipped a copy of Poser 4 before I moved everything over to Poser 5. So I will just uninstall Poser 5 and reinstall Poser 4 and bring back my library contents from the zip. I will then reinstall Poser 5 so I can try it out now and then as the service releases come out.