$(document).ready(function() {	
	$('#main_nav ul li.last a').hover (function() {
		$('#main_nav').css({"background" : "url(/includes/images/external/main_nav/main_nav_bg_hover.gif) no-repeat top right"});
	}, function() {
		$('#main_nav').css({"background" : "url(/includes/images/external/main_nav/main_nav_bg.gif) no-repeat top right"});
		
	});
});