Hi, I have a Pioneer pdp-5050 plasma tv, the kind that has the media receiver. It is not Elite series, if I replace my media receiver with a receiver from the Elite series will my plasma set show a little better picture. It shows a excellent picture already, but also the Elite series are suppose to have a superior picture over the non Elite set.

There would be no reason to do that. And I doubt that it is economical to do so. If you want improved external processing, get a better DVD player (or better yet, an HD DVD player :) ), or AVR. That said, only thing that improves this way is scaling/de-interlacing performance. The only way to get meaningful improvement is to buy a new set.