If you do not have Tivo now you would probably get a SIII style Tivo, that has capability for two cable cards and that will plug into the Tivo (just like a PCMCIA card in a laptop) and the cable card will take place of the cable box. There are two types of cable cards, if you recieve the older version you will need two cards to decode too streams of cable (for the dual tuner), The newer model of cable cards will decode two streams of cable with a single card.