addLoadEvent(randomimage);

function randomimage() {

	if (!document.getElementById) return false;

	if (!document.getElementById('banner')) return false;

  numberOfImagesToRotate = 4;

  firstPart = '<hr class="dashed" /><img src="images/banner';
  lastPart = '.jpg" alt ="" width="760" height="200" />';

  var r = Math.ceil(Math.random() * numberOfImagesToRotate);
  document.getElementById('banner').innerHTML=firstPart+r+lastPart;

}