Seeing the Sony and Samsung side by side, they appeared to be very close in performance with a slight edge to Sony, but I'm not sure it's worth the attitional ~$1k difference in price for the Sony, though.
I've been a Sony fan for years. I had picked out the Sony 50" HDTV I wanted to buy ... shopped it vigorously at all the usual outlets. Finally decided to buy it at Costco. When I went in to purchase, they had a new model Samsung 56" DLP set up right next to it. Same price as the Sony 50" and picture looked every bit as good. I bought the Samsung and a year later I could not be happier with my choice.