Are you sure about that? After getting my 46" rear projection set a few years back, I had to get a "set top box" from the local cable company that could receive the HD channels that I had to subscribe to before experiencing the HD joy. Not exactly a buy, bring home, turn on and watch HD experience. But, once you see HD, there's no going back! I was already told about the drill beforehand.
Comcast has a local office about 5 miles from where I live, so I simply had to drive there, turn in my regular cable box, get a new HD box, plug it in, and then call Comcast on the phone and tell them which HD channels I wanted. For a guy who is software and not hardware, it was easy for even ME!!! ;)