Interesting question. First off, what kind of TV do you have, and what kind of cable box do you use? I'm asking because if your TV is set to one thing and your box to another in terms of display format you'll get a strange mix of picture...

I have an 8300HD, and I use the aspect ratio of the box to set it to normal picture while I have the TV in "Full Screen" mode.

If your cable box has a button that allows you to switch display formats, like the # key on the 8300HD, you can bind it to the remote control. Let me know if I was even close to helping...