Hi there, unless I'm missunderstanding the question, yes you can install Poser5 on one HD and then have the Runtime folders on a different drive. My Poser5 installation is on my main drive C, with the old P4 & PP Runtime on my D drive, and anything I have purchased/downloaded since upgrading to P5, on my F drive (a 120 Gb HD devoted exclusively to Poser) In order to have P5 "see" the other Runtime folders, open Poser, open Figures. This will show the P5 Runtime and the "Download" Runtime (I believe that's what it's called). At the bottom screen is a "+" sign. Click on this and then find your Runtimes. Hope this helps.