$(function(){
		$("img.rollover").mouseover(function(){
			$(this).attr("src",$(this).attr("src").replace(/^(.+)(\.[a-z]+)$/, "$1_on$2"));
		}).mouseout(function(){
			$(this).attr("src",$(this).attr("src").replace(/^(.+)_on(\.[a-z]+)$/, "$1$2"));
		});
});