<!-- Source for chrisdomroll.js -->
  //=====================================================================
  // DOM Image Rollover v3 (hover)
  //
  // Demo: http://chrispoole.com/scripts/dom_image_rollover_hover
  // Script featured on: Dynamic Drive (http://www.dynamicdrive.com)
  //=====================================================================
  // copyright Chris Poole
  // http://chrispoole.com
  // This software is licensed under the MIT License 
  // <http://opensource.org/licenses/mit-license.php>
  //=====================================================================

  function domRollover() {
  if (navigator.userAgent.match(/Opera (\S+)/)) {
  var operaVersion = parseInt(navigator.userAgent.match(/Opera (\S+)/)[1]);
  }
  if (!document.getElementById||operaVersion <7) return;
  var imgarr=document.getElementsByTagName('img');
  var imgPreload=new Array();
  var imgSrc=new Array();
  var imgClass=new Array();
  for (i=0;i<imgarr.length;i++){
  if (imgarr[i].className.indexOf('domroll')!=-1){
  imgSrc[i]=imgarr[i].getAttribute('src');
  imgClass[i]=imgarr[i].className;
  imgPreload[i]=new Image();
  if (imgClass[i].match(/domroll (\S+)/)) {
  imgPreload[i].src = imgClass[i].match(/domroll (\S+)/)[1]
  }
  imgarr[i].setAttribute('xsrc', imgSrc[i]);
  imgarr[i].onmouseover=function(){
  this.setAttribute('src',this.className.match(/domroll (\S+)/)[1])
  }
  imgarr[i].onmouseout=function(){
  this.setAttribute('src',this.getAttribute('xsrc'))
  }
  }
  }
  }
  domRollover();
<!-- End Source for chrisdomroll.js -->