OK, thanks everyone.
I went with PHP require, and it seems to be simple enough for me.
One problem I'm having, however, is that the include files are adding an extra space at the bottom of their respective tables, and it's throwing off the whole alignment!! ...so it's something like this...
<?php require ("www.blah.com/heading.html"); ?>
Here are my heading links...
So on the main page (index.php), it will show my heading links, with an empty line just below them before going on to the next row. I hope that made sense...