Basically I think Poser 5 is better and definitely worth getting! I have 3 machines..Amd XP 1800, P4 Northwood 1.8ghz and a new HyperThread P4 3.00Ghz with 2 gig ram...it works fine on all of them. (flys on the p3 hyperthread!!!) I agree for faster scenes Poser 4 is better, but Poser 5 offers a lot more and now that E frontier has become the parent company then Poser has become a whole new ballgame....its a very strong possibility that Poser could end up with one of the best renderers in the business. Check out their gallery using the pathtracer renderer http://shade.e-frontier.co.jp/en/gallery/index.html this technology will almost definitely find its way into Poser or be able to import Poser scenes. OK Poser 5 was rushed...but its working good now and I dont see any reason to not use it...and it makes a lot of sense to have it so you are on the upgrade path to newer versions. Plus I LOVE THE CLOTH ROOM ...I have written heaps of tutorials for it along with my dynamic clothes packs ..and its great...hey Poser 4 does long flowing clothes that look like shit. Thats reason enough to buy Poser 5 in my opinion, the materials are great too. Nope...get Poser 5 and maybe use Poser 4 for quick scenes...Poser now has a parent company that has some pretty happening software...so get it!!! Thats my hang on it anyway. Cheers Harvey Mann