Currently, I have a refurbished MacBook 2.4 GHz Intel Core 2 Duo that I purchased at the Apple Store a few years ago (see my signature for details). Recently, my mom has shown interest in learning to use a computer so I'm thinking of giving my MacBook to her and purchasing a new (or refurbished) Mac laptop as I was saving up for one for a while. Mainly, I use my current MacBook for e-mailing, surfing the web, MS Office (especially MS Word), and storing/listening to music via iTunes. After doing some research, I'm looking into 13" MacBook Air and 15" MacBook Pro Retina. I like the portability of MacBook Air (I store my MacBook in my backpack and take it to work). However, 15" MacBook Pro's retina display as well as quad core are intriguing. For my usage, which one should I get? Budget-wise, I'm thinking no more than $2k.