I have never used any other version of Poser. I started with Poser5 when it came out and stuck with it through it's service releases AND bugs. Yes it still is slightly testy if you don't compare it to the way it was. It is a definate improvement if you do. (p4 2.6 @512 w/64ddr video) It would be great if Poser5 had support for video cards. I'm sure this would lighten the load on some processors and ease the crashability/lockability on those finicky machines. But as it stands right now, It does what Poser4 does (not pro-pack as I understand pro-pack has plugin support or something, I don't know... and maybe im wrong, like I said I have never used it, I'm going off what I have seen in screenshots and what I have read in the posts here) BUT P5 has the added bonus of a nice Cloth room and Hair room which are both very powerful. The face room is fun if you are using Don and Judy. The Material room is unbeleivably easy and powerful. I saw a screenshot of the P4 material dialog-box. Scary. That alone keeps me pushing P5.