If you have Poser4 on your system already, then just install Poser 5 in a different directory (C:Poser 5 by default) then you can map the library to your old Poser4 content Good old Vue won't even know the difference.. it will continue to look at the old Poser4 file for your license key. I have Vue 4, Poser 4 and Poser 5 on my D: drive and its all fine. (of course being a PC guy myself I dont know about Mac users but I imagine the concept is still the same)