You could use Poser 5 as an excuse to start your Poser installation anew. By this time, your Poser 4 installation may have lots of kinks or problems you don't even know about. Heck, why not keep your Poser 4 installation, and install only what you think you'll use for Poser 5? You can start out using separate Runtimes in Poser 5 to get even better control.