Sheri most high end TV's are HD. Satilite TV has HD channels but you need a HD sat receiver. Many TV stations broadcast in HD and I don't think you need anything extra, just an HD TV. I have long since rid myself of cable but I would imagine you would have to have an HD cable box.
If you don't get off air HD chanels from your local TV sations(some cities have them, some don't) get a satilite dish. There are many HD channels, CBS and NBC now broadcast in HD now.
