$(document).ready(function() {

	$("#nav_list a")
		.css( {backgroundPosition: "0 0"} )
			.mouseover(function() {
				$(this).stop().animate({backgroundPosition:"(-150px 0)"}, {duration:500})
			})
			.mouseout(function() {
				$(this).stop().animate({backgroundPosition:"(-300px 0)"}, {duration:200, complete: function() {
				$(this).css({backgroundPosition: "0 0"});
			}})
	})

});