function menu_over(el,id){
	el.style.background = 'url(images/button_over.gif) no-repeat';
	document.getElementById('button_image_'+ id).src='images/button_image_over.gif';
}

function menu_out(el,id){
	el.style.background = 'url(images/button.gif) no-repeat';
	document.getElementById('button_image_'+ id).src='images/button_image.gif';
}