Problems: 1) So, my 2006 MacBook won't run Lion. 2) I want to get a MacBook Air, but I have 140GB of music. Solution? The reason I have all of this music with me is for long flights, where wifi/internet aren't available. This actually does matter to me. Will iCloud cache the music I most often listen to (say, up to 60-80GB of my most often/recently listened to songs?) ...? Then I could get the 128GB MacBook Air. Otherwise, I might be SOL on this one.