There are various views on this, but I keep my VM at 960MB - for Windows 2K. Rationale is that no Windows (32bit) application can access more than 2GB - it's a Windows restriction. But Poser 5 seems to try to go beyond that 2GB limit at times resulting in instability (understatement ;-). So 1GB + 960MB keeps it "honest". (Why 960MB not 1GB? That happened to be the advised limit for another application on my system, so I stuck with it.)