There are 2 ways to make joomla tableless. The first, harder one is to rewrite all the tables in the components to DIVs and position the DIVs with CSS. This could be very time consuming and advanced CSS skills are required. This is how we made phpzen.com
The second method is a lot easier, there is a package called accessible joomla, it uses DIVs for the content elements, only a few additional hacks needed to achieve a 100% tableless version.
In both cases a css layout based template should be used for getting a joomla 100% without tables