function preload()
{
   var obj = document.images;
   for (var pos=0; pos < obj.length; pos++)
   {
     var tmp = obj[pos].id;
     
     if (tmp.substr(0, 2) == "p_")
     {
        var img_old = obj[pos].src;
        var img_new = img_old.replace("off", "on");
                
        var pre = new Image();
        pre.src = img_new;            
        
        var pre = new Image();
        pre.src = img_old;
        
     }
     
   }
}

function rollover()
{    
   for (i=0; i<arguments.length; i++) 
   {      
      obj = arguments[i];
      var img_old = obj.src;
      var img_new = img_old.replace("_off", "_on");
      obj.src = img_new;      
   }
}

function rollout()
{
   for (i=0; i<arguments.length; i++) 
   {      
      obj = arguments[i];
      var img_old = obj.src;
      var img_new = img_old.replace("_on", "_off");
      obj.src = img_new;
   }
   
}