randomImages = new Array (

  
    '/download.do/id/100138311/','/download.do/id/100138313/','/download.do/id/100138319/','/download.do/id/100138323/','/download.do/id/100138315/','/download.do/id/100138316/','/download.do/id/100138320/',
  

'');

with(Math) {
  var rand = Math.floor(Math.random() * (randomImages.length - 1));
  if (rand >= 0) {
    document.write('<img src="' + randomImages[rand] + '" alt="" usemap="#headerImgMap" />');
  }
}