I have a mid-2007 Aluminum iMac C2E and I have about 50GB worth of HDV video (actually double that; one in the old iMovie format, one in the new) and I want to move one of them (or both) to an external disk. My question is: will editing be really slow? I was thinking Firewire 800 but do you think a USB 2 Drive could handle the job? Or would both be slow? Thanks for your advice.