I'm looking for some advice on an external hard drive for my home pc and laptop. Ideally, I will be using it for storing films, music etc and taking it on tour. There are a few I've looked at which are 500gb and look okay, but I would like one with the capability to work with an external power source or usb (if there is such a thing). I don't want to spend more than Â£100, if I can possibly help it. Any help greatly appreciated.