V5I is perfectly stable and useable, the various patches have done a lot to improve it's stability. However, what will bring it to it's knees are large texture maps. I have 1.5 gigs of physical ram, and if I try to use say two or more Poser objects with large and detailed texture maps then I can watch the memory get steadily eaten up until there is nothing left at which point the programme just gives up. Apart from that the programme is outstanding, with superb lighting options, funtional terrains and of course the ecosystem. Plus much more! Get it - you won't regret it.