So, I have two external HDD, but I want to share one with one imac and one macbook, here's why: (my english it's a bit limited ) My imac is running tiger and I want that HD to backup minor things (plugged with fw400) The mackbook is running leopard and I want the HD to make use of time machine (want to plug by usb) Will this work? Does the drive mount in the two macs when I power it on? Can I access it at the same time even if it's plugged with fw400 to one mac and usb to the other? I would try it, but I'm afraid of losing some data. Thanks in advance.