fwiw;
I'm no tv guru but did just change from a RG59 coax & composite cable box hookup to a box that could use component cables which is the best cabling type my new SDtv with digital tuner offers. Wow, what a difference.

Look at the connectors on the back of the cable box. Look at the connectors on the TV. You need to be able to hook it up with component or better cables for better color and to use HD. Otherwise I think you will have a cable connection and an extra large standard cable pic probably with soft focus because its bigger and not quiet as colorful.

I ran a 42" HD Panasonic plasma panel for several years on basic (NON-digital) cable using my VCR as a tuner. The picture was quite acceptable and watchable. Snow/static, weak signals -- when they occur -- did look worse than on the previous 27" CRT, because the plasma is a larger screen and it shows more detail.

One VERY IMPORTANT step is to properly adjust the picture settings (color saturation, white level, black level, sharpness) to reasonable levels for YOUR room. The factory settings are typically much too high.

It does not matter if the TV is plasma or LCD if the signal coming to it from the cable company is analog or has not been upconverted. The TV's screen will look its sharpest if the signal is brought to it via HDMI, so hopefully your cable box has a HDMI port. The next best signal is via component, so a set of component is needed. S-Video follows. Finally, the yellow-white-red RCA jacks in the back of the VCR or DVD player do not work with digital signals.

Keep in mind that those folks who don't have cable, but have HD TV's with built-in tuners, can still watch any HD and analog free over-the-air TV signals. The tuner will take care of that. However, they must use a VHF/UHF antenna. The HD signals will look nice and sharp on the screen, but not the analog signals. However, soon all the free over-the-air TV signals will be digital.

A final point: folks like me, who don't have cable but watch movies at home, can use one of several DVD players that don't cost very much, but still provide an incredibly nice digital signal. The key is to buy a DVD player that has both signal upconverting via HDMI, and progressive scan. These units are fairly cheap (around $99.00), and are one step below Blue Ray and HD DVD.

What you do is to connect the DVD player to the TV with a HDMI cable, and then change the DVD player's settings to match the TV's capabilities (the instructions are found in the DVD player's manual). Once you have changed those settings and play a DVD movie, you will be amazed!

Component cables allow you to upconvert the signal out of the DVD player, but the signal is not as sharp as HDMI. HDMI is capable of the best signal posible for now, which is 1880i (p).

Keep in mind that not all the DVD movies are created equal. Some are incredibly sharp, while others are just sharp. Some allow you to choose the Surround sound out the DVD player, but not all. For example, you can change the player's sound to English Surround 5:1, 7:1, or other. All depends on how the DVD was burned by the producer.