function swapAd()

   {
   var adPath;
   var randNumber = Math.round(Math.random() * 7 + 1);
   var adNumber = randNumber.toString();

   if (adNumber < 10)
      adPath = "00" + adNumber + ".js";
   else
      adPath = "0" + adNumber + ".js";
   return adPath;
   }

var adURL = swapAd();	

document.write('<script src="_adv/' + adURL + '"></script>');