Hi Patrica Ann

Your computer seems powerful enough, at least you're not using a laptop. So I don't thinks the problem lies there. Did you capture using Firewire or did you use dat, dat, dah... USB? You should only use Firewire as it is the only recommended way to transfer video including audio from camera to computer and then back to camera again if that's your preferred method. I wouldn't use an external hard drive to capture video to, use it instead to back up files and free up space on your hard drive when you are done with a particular project, they're just not as fast as one connected to the inside of your computer.

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