Welcome to DbsTalk! Neither Dish or DirecTV SD channels are a good test to evaluate a monitor. You really need to see an HD program on one of the better HDTV channels. That said, your RCA CRT might be getting soft or need some tweaking. A good CRT monitor is the equal of similarly sized LCD's or Plasma monitors. But they get old and tired after many hours of viewing.
Go for it and if the RCA does not hack it see about getting one of the many LCD HDTV's that are so cheap these days!
Go for it and if the RCA does not hack it see about getting one of the many LCD HDTV's that are so cheap these days!