I just got a airport extreme to share my time machine external drive so I do not have to keep plugging it into my macbook. After the set-up I went to do my first backup over the network and instead of just calculating the changes it started to do a first backup even with the original backup on the disc. Why does it do that? I ending up formatting the backup drive and starting a new one over the network, but a 60gb backup took forever. In the future it would be nice to unplug the disc to recover or backup very large volumes without it starting a new backup. Also my time machine disc shows up on my desktop as a connected server and as a external disc (only during the backup) can you make it just show as a connected server?