A satellite company such as DirecTV or Dish Network will allow you to get high definition programming from them. If you go this route, you will have to pay a little extra to receive local channels if you wish to watch your local network broadcasts. Even if your local networks are broadcasting in High Definition, you will only get standard definition signals as DTV and HDTV take up too much bandwidth. Your HDTV channels will most likely include an east or west cost feed of CBS, HBO, Showtime, Pay Per View, HD Net and so forth. Look at the corresponding pages on this site to see which high definition channels each satellite company provides. If you decide to get HDTV programming from a satellite company you will have to:

Get a subscription from the specific satellite company that includes HDTV programming. Buy a satellite dish that is capable of receiving HDTV signals from the satellite company you wish to receive high definition broadcasts from. Buy a Set-Top-Box that is capable of decoding High Definition channels and is compatible with the specific satellite provider you choose.
Buy a High Definition TV to view the signals.