Oh please follow up. I am committed to MythTV. I have an HD TV and HD Service from my Comcast Cable Card. Still, I have never watch a single TV show in HD. It's not worth losing the ability to pause and rewind. Oh well!

What is this service menu?

Well, long story short, there are no accessible overscan settings in the service menu. I guess these sets have to be tweaked by professionals.

The service menu is a hidden feature. To access it, turn the power off, then hold vol- and input and press power. When it comes on you'll see a purple k on the top left. At that point hold chan- and vol-. You'll then get the service menu. Anything you change here can have nasty results and there's not a lot to change so be careful.