Kim,
Here, I have all three sources. My house Antenna for Locals, like Shannon has said, then I have Comcast and a (personally owned) Satellite Receiver.
The way I've set mine up, is through a Master Amp, which has several inputs, for various DVD, VHS, Sat, Cable, and also have Phono and Tape. And of course, the next slot will be for the DTA. Right now I'm just running Analog, VHF and UHF. Soon, I expect to get a new TV, with ATSC/HD Tuner, and just move the older TV up to a spare room, with the DTA Box, and watch on the new one. (no box necessary then)
I've done it this way, mainly for the Sound System, have several pairs of Speakers, and it is nice. But, with all the Inputs that one of the newer TV's have, they're quickly taking the place of the big Amps, and the sound system on them, is not bad at all.
Besides making sure that a new TV has ATSC/HD Tuner, you may have a choice to get one with several imputs. The more the better, no telling what you may want to imput to it later, and having too many is not enough !

I personally wouldn't buy a new TV, with less than Five inputs, or more.
I don't want to compicate this too much, but i think you need to know, just in case you run across some sets where you have more than one tuner in it.
The older style was Analog and that's NTSC. We'll be dealing with that for another year about, and probably some stations will continue to Xmit in Analog for a while longer. Many of the newer TV's, have both NTSC and ATSC Tuners in them, but those type are probably going to be hard to get soon, and then just phased out, and NSTC will no longer be available.
Next, is the Digital, ATSC, that's the main one for the changeover. With this type Tuner, it can be HDTV Ready, that's where some confusion has arisen, like we've been talking about.
Then, there's the HDTV Tuner component in addition to the ATSC. Gotta have ATSC to have the HD part. I think that there may be some TV's out there that have all THREE of these above features.
Finally, there's QAM, frequently added to some TV's, and it's the one that you would use for your Cable. Prevents you from having to rent their Box, and can save you quite a few bucks over some years. Most QAM TV's also have a "Card Slot", where you can purchase a Card for it, much like the ones you slip into your Camera, and receive/decode the scrambled Cable, making that Set fully functional on Cable. i have seen some TV's which have ATSC/HD/QAM Tuners in them, but, they're rather expensive. Most QAM Receivers will passthrough several (20/25) Cable channels without a Card.
GEES !, and I promised I wouldn't complicate this ! UOOPS !

So, that's the spectrum of what's out there. But at least now, you're armed ! Plus, you can go look, then come back and talk about it too, before you buy.
Good luck, and don't get in a hurry! These new sets can last a long time!
Have a good Day !
