I have a new cmbp with a 750gb hard drive. I'm currently using a little less that 300 gbs. I just got a 1 tb hard drive to use for time machine but am now just reading that the drive should be 2-3x the size of the drive you are backing up. The drive I've got is portable which I think should be nice so I only have to pop it into my computer. Do I need 2 tb of storage? I don't really want to purchase another drive right now because they are expensive and as a college student I don't have a ton of money, particularly right now with getting everything for going back to school. My question is it worth it? I'm planning on using an online back up like carbonite (haven't decided on which yet) as a secondary back up for files. How far back will 1 tb allow me to back up? since documents will be backed up to the cloud and such I don't think I really need to create an archive, just make sure that in case my computer crashes or something I have everything stored.