Sorry if this has been discussed. Since I don't have a progressive scan dvd player on my tv with compression, should I leave my tv on 4:3 aspect ration with dvd's, or change it to 16:9?

You should change your TV to 16:9 with DVDs. That way your player will not have to drop lines of resolution to provide the correct aspect ratio. Progressive has nothing to do with this.

Thanks for the quick response. I did that for a couple of movies, but wasn't sure if I was getting any benefit.

The DVD player also needs to be set to output a 16:9 image.

Already did that. I forgot I had and about half an hour of my daughter watching a movie, I looked over and it was playing full screen(I just put it in and started doing stuff around the house). It took me a minute to remember it was setup for 16:9.