hello. my dad has a surveillance system in one of his stores and he needs an external hard drive that will be able to have great performance (since the system is on 24/7) and a good price (under 120 shipped). i was wondering what drive we should buy. we dont need firewire or eSATA just a good, reliable usb hard drive. i was looking at western digital drives and they seem to be pretty good but im not sure. thanks