$(function(){
 $('.main_menu li.normal a')
 .css( {backgroundPosition: "0 0"} )
 .mouseover(function(){
 $(this).stop().animate({backgroundPosition:"(0 -33px)"}, {duration:500})
 })
 .mouseout(function(){
 $(this).stop().animate({backgroundPosition:"(0 -33px)"}, {duration:200, complete:function(){
 $(this).css({backgroundPosition: "0 0"})
 }})
 })
});