Originally Posted by captobvious

Are you talking about reponsiveness while you're working in the program or the time it actually takes to render the final images?

More RAM and a better video card will make working within the program more responsive, but it probably won't improve your final rendering time that much. This is because what you see while the working in the program uses your video card, but when you do a final render out to images or a movie, it's computed on your CPU. To get the most improvement in your rendering time, it'd be best to upgrade your processor.