Which MacBook should I get? I'm a Petroleum Engineering major, and I've held off on a laptop purchase while waiting for the 13" retina. I'm not sure how much power I'll need, but whichever computer I select, it needs to last for at least the next 5 years. Price really isn't an issue, but I'd rather not overspend. I have about 40GB of data that I need to keep on my HD. Portability is also an issue. I'll be using this in class. Should I go for a 15" retina, 13" retina, or something different altogether?