I know I need to eventually get a new computer for my video work.

Does Wirecast benefit from a video card with its own memory?! My 3D graphics software (Poser & DAZ Studio) use the graphics card to present live preview of our art as we work.

In my experience, I'm always better off buying the most powerful computer I can afford. Would a 27" i5 iMac be sufficient? How much memory should I get? Would an i7 CPU be better?!