HDTV questions


I have some questions about HDTV. Every individual at best buy, circuit city, and soundtrack gives a totally seperate answer, and magzines seem to skip over alot of this stuff.

I live in colorado, Comcast is our digital cable company, and they are now advertising HDTV with thier service.

1) If you have a dish or cable company that sends an HDTV signal, to you need to buy a HD decoder to see HD? Or do the cable boxes do the decoding?

2) Do you need an HDTV to use progressive scan?

3) What types of inputs are requred for progressive scan? the RGB? or does Svider work as well?
slappy
I just got Comcast HDTV in Atlanta. They replaced my existing standard box with the Motorola 5100. I use an RGB component video cable to connect to my HDTV "ready" Sony Wega. S-video cannot carry an HD or progressive scan signal. I get all my previous channels plus 5 HD channels (more to come later). The box also has digital audio out which sends a 5.1 digital audio stream to your processor. Since I do not have a processor, I use the standard analog audio out jacks to send the R and L to my preamp.

My premium channels, and the audio, are better than my previous box. The HD channels are incredible... DVD quality or better. Most of the standard channels are a bit grainier than before. There is an HDTV forum where someone posted that they resort back to S-video, or a standard RCA cable, to improve their basic channels. Thus they use 2 video inputs to their TV. Since I did not get HDTV to watch the shopping channels, I can live without using 2 separate video inputs.
Blueswan...can I ask you a quick favor? I just got Comcast HDTV as well. My problem is that the installer ran the component cables into my 1080i input, and the regular F-pin wire into the normal female F-pin receptor on the back of the TV. Now, when I want to watch an HDTV program, I have to change the TV input to "HDTV," which is receiving the component video signal. Then, if I want to change the channel to a non-HD program, I have to file through all the inputs until I get back to "analog," which is the F-pin, non-HD signal. Have you had this problem? Anyone know if I can do anything about it?
Thedautch, I view all channels through the 1080i input on the back of my set. The 5100 sends all channels through the RGB output. He may have set you up this way because he knows that the basic channels are a bit grainy when viewed through RGB. Try running your cable directly to the 5100, and use only the RGB. If you can live with it, as I can, you only need one video input setting on your TV. If you cannot, use the 5100's S-video out, or RCA video out, for your basic channels. You will still have to use 2 video inputs, but you will eliminate using your TV's tuner for the F-pin input.

Note 1, my Sony Wega is not a true HDTV set, it is "HDTV ready". Note 2, S-video, and RCA video, cannot carry an HD signal. Note 3, I bought the best RGB cable I could find, Tara Labs RSC... expensive, but worth every penny.
The difference between HDTV and HDTV-ready is weather or not the TV has an on-board HD decoder right?

Without the decoder you use the cablebox as a decoder?