Your cable co controls this. Ask them for a "cable card."
Last year I bought an Emerson HDTV that has a built in digital tuner. I was under the impression that all you had to do was plug in your tv to the exisiting cable line and you would receive some digital channels. I have done this but have found nothing. Do I also need an antenna for this? I currently do not subscribe to any cable or satellite television services.
Forgive my stupidity for I thought I understood how all this worked--but apparently not.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic