I am a real estate agent, and I make video tours of all of the properties that we sell. I want to be able to convert the video into iMovie while I am driving from one property to the next, using my MBP. Then when I get back to the office, I will use the iMac to do any edits. Therefore, I want an external HDD to make the transfer easier. Now for the recommendation, can I use a firewire portable HDD that doesn't need an external power adapter, or should I go ahead an get one with the power adapter? I am thinking I will go with a 500GB 7500RPM drive. Any help is appreciated.