So many things factor in when it comes to settings, video source, signal strength, tv, etc. But, yes, it's likely your cable. I used to have comcast. I switched to comcast 'digital', and was VERY unimpressed with it. I then went to DirecTV, and the sound and video quality were both very impressive. Reason being, with 'digital' cable, it's still not a pure digital source.. it fed to your carrier, and they feed it to you. And, in addition, they don't tell you that many of your stations, especially your local stations, are STILL analog (same as regular cable). With satellite, each person is getting a pure digital feed from the sky, right to their dish.. no routing/re-routing through various sources before getting to you TV. And, it's cheaper than my cable was.. Try it, you won't be disappointed! You may/may not continue to have trouble with standard (non-HD, non-DVD) channels.. some people do, and some say they don't. Again, many factors.. the connections they choose to use, settings, etc. But satellite should show you and improvement. And look at it as a long-term investment. In a few years, everyone is going to be broadcasting their signals in the format that these TVs were designed for (more HD channels).
I owned Toshiba 52HM84, I have Charter Cable and the guy came to my place and install the HD Reciever box. However, the quality is not as good as when I saw it at Best Buy. Is that because at Best Buy they used Sateline and I'm have cable. Because it so much different in the Quality of picture.