I'm looking to buy a MacBook, but I'm not sure which. In that I'm only going to use it for minimal purposes--hitting the internet, Final Cut, Word, some games--I'm think i could get by by saving some money and getting a previous iteration. How far back can i safely go before there's a drop-off in power/quality? I'm pretty computer dumb, so what do I need in terms of RAM, etc? Thanks very much.