i have both. i prefer my older macbook. i am using it right now as my brand new pro sits in the box (yes, i still have it in the box because it refuses to run some of my important programs - baffling, i know).
the pro is awesome, i just haven't gotten it to work properly.
the macbook is definitely more sturdy. the polycarbonate case is really tough, it just gets all swirly the instant you wipe it clean, even if you use a microfiber. but it could, hypothetically, crack. however, the aluminum is one piece, so it's pretty tough too. but if you dropped it, it would get bent to shit.
but honestly, if you drop either, i think they would be pretty jacked.
one thing i noticed about the aluminum case - it has really sharp edges, especially where i normally rest my wrists when typing (the macbook pro feels like it's going to go angelina jolie on me and slit my wrists).
it's a weird design choice, and it makes me want to wear beastmaster's wrist gauntlets when typing, but who are we kidding? - i would want to wear those anyway.
good luck. i recommend going to an apple store and just playing with all of the machines they have until you really have a good idea of the pros and cons of each.
