var menu1 = document.getElementById("menu1");
var menu2 = document.getElementById("menu2");
var menu3 = document.getElementById("menu3");
var menu4 = document.getElementById("menu4");
var menu5 = document.getElementById("menu5");
menu1.onmouseover = menu2.onmouseover = menu3.onmouseover = menu4.onmouseover = menu5.onmouseover = function(){
	this.src = "bg/"+this.id+"_mo.jpg";
}
menu1.onmouseout = menu2.onmouseout = menu3.onmouseout = menu4.onmouseout = menu5.onmouseout = function(){
	this.src = "bg/"+this.id+".jpg";
}