I have the HD from a Mini (whose main board died) in an enclosure connected by firewire to a new macbook. The mini had/has OS 10.4.6; the macbook is 10.5.1. This works ok as an external storage for the macbook. I don't know the condition of the OS on the external drive as one of the accounts has zero size, so some damage must have occurred when the mini died. However, the Macbook's disk verify said the external drive looked OK. I tried starting the macbook with option held, and selecting the external, but 'About this Mac' still said 10.5.1, so presumably the mini drive's OS won't boot the macbook - but then Tiger wouldn't boot a new Leopard macbook anyway would it? Anyway, (stupid question alert) if I'm just using the external to backup individual files and extra space, can I literally delete all folders shown in the Finder from it other than 'documents' and 'music'? Would there be any problems installing Leopard on this external mini drive so I can use it for a full macbook backup/disk image (it's 100G; macbook is 80G)?