I just bought a 320 gb serial hard drive to replace an 80gb hard drive in my iMac. I loaded disk utility and transferred all the data to the 320gb using an external case but when I physically switched it out, it doesn't boot from it. It just has the folder with the question mark. Why is this and how can I fix it? I'm now trying to load off the old drive using an external case but I cannot remember the shortcut that allows me to load off the external. How can I do that? Thanks a lot for your help. The drive is usb, which I've read can be a limitation but I have leopard on an external drive that I'm able to easily boot into by just selecting it in system preferences. I basically just want to do the same thing but by pressing a key on boot up instead of selecting it in system preferences and then restarting.