MacBook recommendation?

Would a new 2.0GHz MacBook (w/ Intel processor) work sufficiently fast to run Toon Boom Studio? Would the 13-inch screen drive me crazy? Does anyone know if a 2.0GHz MacBook Pro w/ the larger 15-inch screen would improve performance enough to justify the extra $600 or so? I’m a high school teacher and not wealthy! I’ve been using an iMac G5 (old processor) w/ 17-inch screen to run TBS at school and am very happy with it, but need to get my own laptop now. I know personal requirements vary, but would still appreciate some other people’s opinions. Thanks!