var prel_img = 2;
var preloaded = false;
var temp_img = new Array;
function prel(){

   	if(document.images) {
	  for(i=1;i<=prel_img;i++)
               {str = '/buttons/b' + i + '_o.gif';
               temp_img[i-1] = new Image();
               temp_img[i-1].src = str;
}preloaded = true;
 		}
}
function on(im){
	element = document.getElementById(im);
	if (element && (preloaded == true))
		{element.src="/buttons/"+im+"_o.gif";}
		
}
function off(im){
	element = document.getElementById(im);
	if (element && (preloaded == true))
		{element.src = "/buttons/"+im+".gif";}
}