I have Pro Pack, which was much more stable than Poser 4. I also have Poser 5 which, so far, is more stable than Pro Pack. The big question is do you want to render in Bryce, or Vue or LIghtwave, etc. If you do, stick with Pro Pack. None of the new stuff will work in any of those and the Poser to Vue transfer that was so easy is lost with Poser 5. Though some people have found work arounds. Also, if you are planning on doing animation, forget 5, it is probalby too slow and buggy a renderer-- collision detection is too iffy for animation. If you plan on getting tons of clothes, models, characters-- if you want everything that's out there to work with, consider getting Poser 5. I was spending at least an hour rearranging my libraries because only Poser 5 allows imbedded folders and Poser 4 goes terribly wonky with over full libraries. I had to learn Poser 5 because I had NO room for V3. I'm not sorry. If you have a powerful processor and lots of memory, you will probably have little trouble with Poser 5. If you have less than 800mhz, and less that 512 ram, well, you'll have problems with hi-res textures in any Poser but those can be resized. Some people run Poser 5 with fairly weak processors-- I don't know if they only use Posette or Judy. I don't know if they run big scenes. I'm leery of trying big scenes myself and I have 2.4G and 2 gigs of ram. I want a bit more virtual space first. Poser 5 is not as tough a learning curve as I thought if you take it slowly. I really like firefly. I also like the dynamic hair, though I don't make my own, I buy the Rdna hair that's designed for quick renders. It really is and really works about twice as fast as other hair. Emily