Confused newbie - why do so many channels have cropped pics?

We just bought our first LCD - it's a 40 inch Samsung. We have our cable through Cablevision in New York.

We're a bit disappointed that we have so few channels that take full advantage of the new television. Even a lot of the HD channels have images cropped on the sides. Is this because the networks send out the same image just in a higher resolution?

The only channels that make use of the whole screen seem to be movie channels and PBS' high definition channel.

We're just trying to figure out if we have some of our settings wrong or if it's a matter of waiting until there are more hi def channels.

Thanks for any help!

There are simply a lot of channels that don't produce HD 100% of the time.

Discovery HD is one where you should see HD all the time. You will also see HD on most of the major networks (ABC/NBC/CBS/FOX) at night. 8pm-12am most of these have High Def content.

I'm not that familiar with Cablevision in NY, but I don't think they have the same amount of HD channels as many competitors. If you can switch to something else, you may want to look at your choices.

Make sure your TV and cable box aren't using any stretch/zoom features. Those tend to crop the sides of the image too.