Use the CSS and XHTML for the main layout and then just use the tables for search results etc..keep it lighter, rather than full of tables..
You can actually place php content within the CSS boxes.
just opt for the <?PHP echo $pageheader; ?>
option etc. That's what I'm doing on my latest project..I'd link it but it's still in testing stage..
If you build the database in MySql, just download an app like PHPrunner or PHP maker and that will build the CMS for you to match your DB..