idk, I can definitely see a difference. Maybe its a combination of my ram and the 72000rpm drive, but my OS loads in <20 seconds, my 5,000 picture iphoto library loads instantly, same with my 7gb of music in itunes. For me, its a whole new computer. My fans never turn on. I constantly run spaces with safari, mail, itunes, ichat, word, and excel while streaming music to an airport express and burning a dvd. I can't get my fans to turn on. Even photoshop and illustrator load instanatly. Maybe I'm imagining things, but compared to a 160gb 5400rpm stock, my 200gb 7200rpm is an improvement