Poser doesn't do much with the registry, due I think to its origins as a Mac application; just a few file associations and stuff. I think I once ran an uninstalled version of Poser off my old hard disk after I demoted it to a data disk and reinstalled Windows on a new disk. That was probably P4. Try it; I don't think anything bad will happen. You may end up with some extra registry entries, but if your company is tolerant enough to let you run Poser at work, I don't suppose they'd worry about that.