My system is nearly complete new TV, Toshiba 37HL86 new AV reciever Yamaha htr5960 Star Choice DSR505 HD Sat reciever and an older Samsung progressive scan DVD player

HD TV Blew me away at first. and watching a DVD is a pleasure compared to the old TV but I need to know

When I watch a DVD there must be some form of upconversion by the TV. after reading a few articals on the web about upconverting DVD players, I was wondering how much better is the picture in such a player. Is it worth laying out another bunch of cash for an Upconverting DVD or is the TV doing a fine the job.