Im deciding between a couple samsung dlp tvs, one of them has a firewire and cablecard connection. What can the firewire port be used for? At Frys I saw a tv with a external hard drive connected to it via firewire and they were showing video. I asked the salesperson but she had no idea how that works. how does that work? how do you select what u want to watch? does the Tv have some built-in software? Also, is cablecard useful?