scott mentioned mike gyver's adapters where an airline plug is spliced into a standard magsafe adapter.

you can use a 60 watt adapter (and a 75 watt inverter on the plane), however, i'm saying it's easier to just get the apple airline adapter. it's a lot less hassle than fumbling with adapters and inverters. the only drawback with it is that it only supplies enough power to run the computer; it won't recharge the battery.