I have P5 with the latest service pack running on an Athlon 1.6mhz with 500 MB RAM. I have yet to encounter a serious problem with anything I've tried to use in P5, including fringe functionality stuff like Easypose, that I thought would get broken by P5 for sure (good thing somebody at CL thinks Easypose is as cool as I do!) The Firefly renderer has virtually eliminated the need for me to do the labor-intensive "port Poser objects over to a real renderer" thing, at least at the JPG level. Add in procedural textures (FINALLY!!!), dynamic hair and cloth, and divide it all by a super-cheap pricetag ($169 to upgrade!) and you can't lose.