I have a number of scrapbook style pages created in Photoshop Elements
4.0 that are sized to 8.5 X 11.  I would like to create a slideshow
out of them and then use them as part of a DVD that I am creating
using Sonic DVDit 6.0.  When I create the slideshow (using either
program's built-in function), I lose part of the text on the top and
bottom when the DVD is shown on a TV, the slides look fine on a
computer monitor.  What is the correct size that the pages should be
resized to before inclusion in the slideshow so that they fill the
largest amount of a standard TV screen (not widescreen) and still do
not lose any of the page?

Hello
You must begin working with pixels. Inches doesn`t matter on screens.
So find a way to resize your pictures.

There are different standarts for TV sceen sizes. If you are using 4x3
PAL the screen size is 720x576 pixels and the safe area is 576x462
pixels.

So you must put your pictures (576x462 maximum size) in the center of
720x576 layer with some background.

A good way to do that in Photoshop is first to resize your image
ALT+I+I (safe area size max) then to resize your canvas ALT+I+S (NTSC
or PAL screen size with some color for background)If you use this
technique don`t worry for the center alignment.

If you are using 4x3 NTSC the screen size is 720x480 pixels and safe
area size is 576x384.

My advice is to use NTSC safe area size if you don`t know what you are using :) 

You can find more information about safe area here:
http://en.wikipedia.org/wiki/Safe_area