The built in tuners are for accessing channels via the Antenna Input. You can hook up an indoor or outdoor antenna, or your cable, directly to that input, and then run the channel installation process. With an antenna you should receive all the local HD channels, depending on how far away you live from the transmitters. With cable, you should receive all the standard cable-ready-TV channels and all the local HD channels, but you won't receive any higher-tier scrambled digital cable channels. To get those channels unscrambled, without a cable box, you need a cable card (that is if your TV has a cable card port and your cable company offers a cable card). Rental of the cable card is usually about one-third the cost of a cable box. You'd still need to pay for higher-tier digital channel packages and premium channels if you want them unscrambled.
Philips 42" LCD HDTV (model 42PF9831D/37)
Dish Network ViP722 & TWC Cisco 8640HDC