Do I need one, if so, which one?

I have a Mits WS-65869, and my input sources are DirecTV and DVD. While the picture from DVD is pretty good, it can appear slightly grainy (progressive scan). The DirecTV is not quite as good. While some channels are pretty good, I am an avid sports fan, and get many artifacts and distorted images while watching football and hockey. Would one of these solve the problem, and improve the overall picture? While they also improve on a progessive 480p signal? Additional, how noticeable is the difference, and are the jaggies really eliminated? I'm guessing I was going to be in the 1-2k range, and would like recommendations, or if I need to go better, or if lessor would be just as effective. Thanks