I am new to this, but since I have a MBA, drive space is a concern. I'm curious to back up my core system (about 20gb) to the cloud instead of a Time Capsule. I have a free dropbox account, I have looked at Mozy and iDrive. Anyone do this? Would Time Machine make a local backup and then sync it? I obviously don't want it back up to the main drive.. Point me in the right direction?