I currently own a 2.33 ghz 17" macbook pro, and I am saving up for a new 15". As I'm getting closer to reaching the right amount of money, I'm having trouble deciding what to do. The pro i have now is used extensively, and with money being a factor, I need to decide which 15" to get. Should i buy the 2.53 ghz with a 500 gb 7200 rpm HD, or the 2.66 ghz standard? please help!!!