Well, I jumped from Poser 3 to Poser 5, and I'd agree 100% about more RAM. But, with Poser 4 re-released as Poser Studio, and the sheer volume of extras that are P4 compatible, either option is good. But with P5 I've struggled to figure out how to do stuff. Most of the tutorials are aimed at P4, and there have been a lot of user-interface changes. P5 seems to be aimed at the more experienced user.