Poser will generally only use one of the CPU's. As far as I can tell, it's not wired for multi-processor support. That said, if you're doing a long render or something you can let Poser eat one CPU and do something else with the other. I was doing multi-hour Python script runs and I could still do email, web troll, word process, etc on the second CPU while Poser chugged on the first. More RAM is always better. Right now it's so cheap I'd buy all you could.