I am currently running a P4, 2.25ghz with 1 gig of DDR RAM under WinXP home. In fact, it is currently a crime scene animation in Poser 4 (Since Poser 5 chokes and pukes on it everytime). I can't tell you if the difference in render speed is so much the additional RAM on this system or the processor, but until loading Poser 5 I had not EVER had a lockup or crash on this system. It ran Poser 4, Cinema 4d, Vue d'Esprit and TrueSpace with no problems and at a speed that is, well... delightful. We won't go into the Poser 5 issue. If you can afford it, get the additional DDR. You won't regret it. Take care and be well. casamerica