Ahh - my only problem with your choice was the RAM. Apple likes to pork people over that. Should try and downgrade your ram choice, and buy it 3rd party via Crucial or a competitor. No idea what Apple gets for ram now, but last year they wanted something crazy like 750 bones for 3 Gigs in the imac. And I bought it third party for 150. So unless it's a standard offering, or you do NOT want to put in your own ram - try and put that cash towards something else.
Is it easy to replace ram in the macbooks? Is there a slot opening?