I've been considering a MacBook Air because the most power I'll need is for composing music (and I don't mind the exclusion of a cd/dvd drive). If I were to carry all of my music and music related files on a hard drive I would be using upwards of 250 gigs (which would leave little room for other things). I wanted to run my solution by some people to see if this was possible, and if I am missing some sort of limitation. I would have a 2.5 in external hard drive attached to the usb port on the back of the Time Capsule. I'm assuming I would be able to access this drive from the MacBook Air and work with it pretty easily and untethered while at home. When I need to be on the move I could just unplug the ext hard drive and plug it in when needed (which won't bother me), thus giving me access to a larger hard drive when necessary. How does this sound? And if this does work, are there backup solutions for the external drive?