I'm going to university this coming fall and will be busing to and from school everyday. I am a very petite girl (90lbs) so I prefer a portable laptop. Since I'm so small I don't want to carry a heavy laptop around campus. However, I'll be doing some graphic works and will be using Photoshop quite often. I'm going to be a Marketing major so I'll probably do some video editing. I want my laptop to run smoothly! I am debating whether to chose the 13-inch: 2.9GHz dual-core Intel Core i7 or the 15-inch: 2.3GHz quad-core Intel Core i7 I'm not concerned about screen size that much. Is the 13 inch good enough? Is the 15 inch light enough for me to carry around campus everyday? PLEASE HELP.