Hello. I'm deciding between the base 13" or the base 15" mbp. I am looking for a laptop that is portable. I will be using it mainly for internet, word processing, powerpoint, excel, and occasional movies in the form of dvds and youtube. I feel that both models are portable for me so what I need in a laptop are the following: 1. Longer battery life. 2. Less heat. (I would like to use my mbp on my lap.) 3. Reliability. (I want to own it for a long time.) One other thing. I like the smaller size of the 13", but it bothers me that the speakers are underneath the laptop. The 15" has the speakers on top, next to the keyboard. Any advice on which laptop to get based on the 3 criteria? Thanks!