I'm thinking about purchasing a MBP during the Friday sale (hopefully there will be some good deals). I wanted to get either a 2.4ghz 13" with an upgraded 8gb ram or the basic 13" 2.66ghz with no upgrades or the basic 15" 2.4ghz with no upgrades. I've done some research but still cannot make up my mind so hopefully someone out there has some more information that can help me out. Which laptop would be faster? And are there any significant differences? Thanks in advance!!