function scaleTable() {
	var height = $('cols').getHeight() - parseInt($('header').getStyle('height')) - parseInt($('footer').getStyle('height'));
	$('nav_col').setStyle({
		height: height
	});
	$('content_col').setStyle({
		height: height
	});
	$('right_col').setStyle({
		height: height
	});
}
Event.observe(window, 'load', scaleTable);