With my old machine, I do get noticeable pauses when I'm switching tasks--render back to preview, for instance. My understanding is that Windows version is important to get the best out of multiple core processors. My experience is that you must install manufacturer's graphics drivers if you want good OpenGL support, rather than relying on Microsoft.

Current standard hardware is better than what I have in my machine, except perhaps for the quantity of RAM. Choosing the graphics card is important, especially if you think you might want to use software other than Poser.