Are many 13' machine this heavy? I can't tell the difference in weight between MB and 17' MBP! Theres a big difference is size but they weigh the same? I really think its a bummer, because it makes the MB hard to carry around... particularly with 1 hand... The Air is much lighter, but I am not sure the weight gains are worth it!? If MB got SSD and didnt use hard drives(i imagine the HD is the heaviest thing in the machine?) how much lighter could the machine get(and thinner)?