I see comments like these all the time - how in the WORLD do all these MacBooks just spontaneously break? If you ask the owners of them, they never drop them, they never set anything on them, or stuff them into a backpack, or drop anything on them, etc. - they just break coz of poor build quality.
Whenever I hear a claim like that my BS detector goes haywire. I've had my white MacBook for two years now, I travel with it in my briefcase, I let my 3-year-old use it, and there's not one crack anywhere on it. Put a wrist rest cover on it and it doesn't even turn yellow, either.
I won't deny that aluminum is more durable than plastic, but come on, even plastic doesn't just break on its own.