i'm going to get either a macbook or macbook pro, but i want to talk to someone who has owned both of the new models. i have an older model of the macbook, and the plastic is cracked all over the place. i don't want to deal with that again. does the new macbook model have cracking issues as well? and as for the pro, is the body a lot sturdier? i want to get a computer that won't dent and scratch and crack so easily. finally, if i were to upgrade the macbook to 4gb ram then it would have the same ram and processor speed as the pro... so would the macbook function exactly the same as the pro?