I'd go for P5. If you don't have the preconceived notions of how materials work in P4, P5's material shaders will just be a learning experience, and P5 is soooo far and away better than P4 in this regard. On top of that, P5 includes real dynamics for hair and cloth, when you want to get into that. Your machine is fast enough that P5 should run fine (I run it on a 1.7GHz Pentium 4), but I would recommend at least 512MB of RAM (more if you can). Additionally, though the new renderer won't win any speed competitions (except maybe going up against Bryce :) it is a pretty decent render engine. Many people have said that they don't see an improvement over P4's render engine. That may be true when rendering things that are just using straight bitmap textures (such as many products designed to also work with P4), but the new render engine really shines when combined with procedural shaders from the material room. I think perhaps because procedural shaders are new to the Poser world, even a year and a half after the P5 release, many people are only now starting to make much use of them. Anyways, I'd definitely recommend P5 over P4 if you are at all serious about 3D in general. For example, even if there is a bit of a learning curve to the material room at first, P5 has one of the friendliest shader network editors, and concepts learned here will transfer into other 3D apps. My $0.02 :) -Jeremy