The tv converts every signal fed to it to 1024x768 (its native resolution). 480p is converted to 1024x768, just like 1080i is converted to 1024x768. Upconverting may look better if the dvd player converts to 1080i better than the tvs internal conversion, and if the tv converts the 1080i to it's native res better than it does 480p. Test which looks better to you and use that.