function switchMenu(obj,img) {
var el = document.getElementById(obj);
var imgobj = document.getElementById(img);
if ( el.style.display != "none" ) {
el.style.display = 'none';
imgobj.src = "images/arrow_right.gif";
}
else {
el.style.display = '';
imgobj.src = "images/arrow_down.gif";
}
}