Even with the considerable sum you have put down on your entertainment devices, some home theater projectors would be wont to display only the sharpest pictures and unfortunately, that would not come from your standard definition channels. It gets even worse with wider screens because they are notorious for throwing off the scaling when enlarged. With HDTV, there is that matching of the resolutions from the signal to the TV so the resulting picture you get has less distortion and will have a marked difference on the intensity of the colors. To ensure that your home theater is taking advantage of all the clear, and sometimes free, HD programming out there, pick the best option to suit your existing devices and budget.
Getting HDTV from over-the-air networks
Most of the major TV networks in the country have jumped into the HDTV bandwagon and, if you have an HDTV-ready set, all you need is the tuner box to receive the HD signals. This is, of course, assuming that you already have an antenna in place for your standard definition channels. Depending on how far the network’s tower is from your house, you may need to put up an antenna on your roof if the usual rabbit ears will not suffice. Even if you have to make a one-time investment on the tuner, the programming is free of charge so as soon as you are done with the initial set up, you are good to go.
Plugging in to HDTV cable service
If you wish to get your HDTV programming through a cable service, you have to sort through their marketing lingo and make sure that you are not only getting their digital cable package that broadcasts on standard definition. Some providers add a premium on HD channels so you could end up paying a slightly higher subscription fee. You might also be renting out, for minimal cost, their HDTV-compatible box so factor in these costs before signing on a long-term contract.
Receiving HDTV through a satellite
With satellite TV programming, you can inquire about HD upgrades on your basic package. This is to ascertain that your dish and receiver are both HDTV-compatible. This means that your old satellite dish that is receiving standard-definition channels may not work in this set up.
Source: http://www.lcdhdtvtelevisionsreviews.com/getting-hdtv-into-your-home-theater.html