Hello, I have just got a 1Tb external HD which I would like to use with time machine. I currently have a 320Gb internal for all my applications- mainly for audio purposes. I record directly onto this. I also have a 320Gb external for all my music, video, pictures and archived files. This is at about 70% capacity. My internal drive is only using about 100Gb for my OS and apps. I would like to set up the 1Tb as a back boot drive and a time machine back up for both hard drives. If I partition this, how much space do I need to leave for a boot drive and how would I go about this? thanks for your help.