I just bought a new MacBook (white, 2.0, SuperDrive refurb for $849). It comes with a 60GB 5400 RPM HD that I'll have to replace. This is my first MacBook, so I have a question: Should I go with a 5400 RPM HD or a 7200 RPM HD? Or, in other words, how will a 7200 RPM HD affect battery life on my MacBook, and what will the increase in performance be (versus a 5400 RPM HD)? Which is the better decision, balancing performance and battery life?