You can do this with conjunction of jQuery load() and adding a new div to contain the content of the site:
head (divs)
--------------------------
container div
left (divs) | right (divs)
/container div
So you, do something like this.
$('#container').load('ajax/test.html #container');
See the documentation for jQuery load, it let's you loading into specific elements and filter which part of the html to include.