Hi Dawn,
I've used a modified version of this zip file on my latest project. (I changed it from tables to Div tags on the "main" file.)
This makes it easy to change layouts because all common elements can be loaded onto the "common" file.
Works well and pages load fast because those "common elements" are only loaded once. The only part that changes is the "content" of each page.

http://www.phpbuilder.com/columns/kendall20001122.zip

Once you get the concept down it's easy to make different latouts by making a copy of the "prepend", "common", and "main" files and renaming them to "main2" etc... Then just change the "common2" layout.
Sounds complicated but it's not.
Hope this helps.
Robert