I gave up cable years ago. I get decent over the air HDTV in Stoughton. Not foolproof but usually pretty good. Add Netflix streaming, YouTube and Amazon ondemand thru my Tivo and a few odd websites and I watch pretty much anything I want. Sure I might have to wait a day or month to do so, but it's not that big of a deal to me.
If you're using a computer hooked to your tv and the picture looks bad it's most likely because you have the resolution of the computer at something the tv can't handle and it's scaling the video. Scaling video is pretty much anyways a bad idea. I've had good luck using pretty much any hookup method (hdmi, s-video, etc) as long as you set the computer close to the right resolution.
The problem is lot's of computer can't output the proper resolution that a tv wants to see.
One of the main benefits of using something like the Roku, Apple TV or Tivo boxes is they output streaming video at the right resoltion.
Here's a good article on resolutions. Try and get as close as possible to the tv's native resolution for the best results.http://reviews.cnet.com/hdtv-resolution/