Gordon - I just tried it with my 510 and Sony HDTV. The 510 created a letterboxed image within a 4:3 picture, leaving left and right bars. In order to fill the wide screen, I had to use the Sony's "Zoom" format setting.
I then compared picture quality between that and what I had been using, which is the 510 set to 4:3, and the Sony's format set to "Wide Zoom".
Quite frankly, using the Sony's "Wide Zoom" with the 510 set to 4:3 looked much better. I would imagine your widescreen TV would also provide similar results.
OTOH, when my DVD player is set for 16:9, it fills the Sony perfectly, instead of creating a letterboxed image within a 4:3 picture.