beater:I have been thinking of changing my blu-ray player to one of the new sony or panasonic players, but really how much better will they be over my current player.
From memory, your TV is an HD Ready - not Full HD - design, and doesn't support native 24fps. So you're not going to see the full benefits of a newer player (though you may enjoy a sonic boost).
Personally, i'd save your pennies and either spend them on more Blu-rays or put them towards your next TV. You've got a great BD player I see no immediate need to upgrade in your set-up.