I'm not an expert. I'm looking to buy SOON (tomorrow even?). 15 inch is first choice, 13 inch is cheaper. Some pro-Apple IT people I know love their MBP but mention that the 5400 HDD slows down the i7. Yet the 15 inch, in particular, is considered "a beast." I imagine the size of the HDD plays a role too (at least if it's more than half full). Finally, why hasn't Apple switched from 5400 to 7200 --- battery life, noise or ???. (Not complaining, this is my dream machine --- 6750 card, really nice screen, gorgeous, quality feel, nice to type on, slim, good battery, customer service exists, and so on. Plus, helpful people on boards like this.) Is it fast due to OS X being faster than Windows? Or ??? (And not that speed is everything.) (The MBA SSD is too small for me and I suspect it could heat up quickly; plus I want an optical drive.) Thanks! Close to buying!