I think you're right. It looks like the public_html area has all the folders found in the new moodle 2.8 structure, so I'm going to put the moodledata.backup back where it was, backup my public_html, then install 2.8 under public_html. Although, I may try a new folder so it's not comingled with the other web applications there and see how that goes.
Thanks for your guidance.