Well, Boot up poser and and all the other apps you have running at the same time. Pick the most complicated scene as well. Now bring up your task manager and see how much is shown in performance under the commit charge total. If your total is well past the total physical ram you have, you might want to buy more ram. Mines showing 170megs in win2k with just a few windows and internet explorers running. But my Largest scene in bryce brings it to 1.15gigs total ram committed. In that particular picture, when i went from 512 to 1gig of ram i found a major change in performance. Due to the lack of harddrive swapping.