$(document).ready(function(){

	$(".menu_item").hover(
	function () {
        // Replace img src with rollover image.
    	var rollover_img = $(this).attr("src").replace(".jpg","_rollover.jpg");
	    $(this).attr("src",rollover_img);

	},
	function () {
		// Put back the original image
		var original_img = $(this).attr("src").replace("_rollover.jpg",".jpg");
		$(this).attr("src",original_img);
	}
	);

});