I currently use a Time Capsule for Time Machine backups. I want to get a second external HD and also put a backup on that in case the TC dies. Is this as simple as selecting the new disk in TM preferences and doing a backup? After this is done i'd like to go back to using the TC for regular backups. Has anyone used Time Machine to back up the same computer to multiple external hard drives? Any drawbacks or things I should know or worry about?