We need to buy ds a laptop for college and he'd like a Mac. I looked at the website and can't tell the difference between a macbook and a macbook pro. Can someone explain it to me? Is a 13" screen a decent size? I know he'll want to skype and watch movies on it. His school actually will supply word for the mac for free. I would also like something that I won't have to upgrade in the next 4 years. Any thoughts? Thanks!