All these tips are nice. But, the fact is most Dish SD channels look like crap on a large TV, especially the local channels. They over compress them to fit them all in the limited bandwidth they have. You can try this and that. But, they will still not look very good. Also, SD will often not look that good on an HDTV, regardless of your provider.
You can make them look less crappy by adjusting your TV and changing to a different receiver. If you go into the TV's menu, and picture settings, you should be able to change it to "movie" or "pro", if you have a Sony. Those settings look much better than the harsher "dynamic" or whatever comes from the factory.
The 811 is a horrible receiver. But, I'm not sure exactly how the receivers work with these multi-dwelling systems. That may be the only one they offer there. I don't know. But, if you're not subscribing to HD, why did they give you an HD receiver? Also, why not subscribe to HD to go with your HDTV. The Bravia has an awesome HD picture.