Not being facetious, but the real answer is 'it depends.' Poser doesn't do multi-processor support, so as far as it is concerned your second processor will be of no benefit other than letting you work on other applications whilst Poser does a render. OTOH if you use a multi-threaded application like Maya or Max, they do take advantage of a multi-processor environment. So if you'e mainly a Poser user with a little Maya thrown in then go for the single processor. If you mainly use a high-end, multithreaded app but use Poser for making your figures and then render back in your big app, go for multi-processor.