Hi everyone ... so i finally got an external Western digital 320gb passport for my Macbook with 160gb. I have some questions and was wondering if anyone can help... here's my situation: 1) I'm not interested in hourly or even daily automatic backups. I was thinking that I'd plug it in once or twice a week. Correct me if I'm wrong... but it seems to me that I can leave time machine OFF and at the same time tell it to BACK UP NOW. Basically, I could operate it manually. 2) The second thing is how much space time machine takes up... it says that it never deletes weekly backups and will fill up the drive. I was hoping that since my new external is twice as big as my native drive, I could make only back up up the 80 gigs of crucial stuff and then use the extra few hundred gig for "disposable" stuff. So the second question... how do I keep time machine from eventually devouring all my stuff? thanks for any help!