I am trying to decide on which model will best suit me. The most power intensive use I will need is using Lightroom 4 for photo editing. Otherwise, the basic web, email, iTunes etc. No gaming. No video rendering etc. I have ruled out the 15" too big for my liking. Basically, my question is if the extra processing power is necessary for my needs. If I got the base model, upped the RAM and an external hard drive if necessary, would that suffice? I also will consider an external monitor. Thanks for the replies!