How long is a piece of string? :) Seriously it depends on what size and quality. Maybe give an idea what you are rendering and people can give a rough comparison. With systems, a good way to speed up, almost essential for animations imho, are a few extra machines. This will improve you speed dramatically, far more than extra ram etc. You can build little shuttle systems for a couple of hundred pounds with no monitors etc. Bare bones and a good cpu. I am guessing you are thinking it is taking a while to render your animation?