I'm not very smart with Time Machine. I have a 150G drive in my MacBook. I've got a 150G partition on an external drive dedicated to Time Machine. I've been trying to back up today but it's telling me I don't have enough space on the partition. Now after messing with it to try and get it to back up (unsuccessfully) I've given up and ejected the external drive. Now my MacBook's HD icon is turquoise with the Time Machine logo. What the hell did I do? 1. Should I really be using a bigger drive to dedicate to T.M.? 2. Why doesn't T.M. just wipe the old backup and use the space for the new one?