function initRollovers() {
     if (!document.getElementById) return

     var aPreLoad = new Array();
     var sTempSrc;
     var aImages = document.getElementsByTagName('img');

     for (var i = 0; i < aImages.length; i++) {		
          if (aImages[i].className == 'imgover') {
               var src = aImages[i].getAttribute('src');
               var ftype = src.substring(src.lastIndexOf('.'), src.length);
               var hsrc = src.replace(ftype, '_o'+ftype);

               aImages[i].setAttribute('hsrc', hsrc);

               aPreLoad[i] = new Image();
               aPreLoad[i].src = hsrc;

               aImages[i].onmouseover = function() {
                    sTempSrc = this.getAttribute('src');
                    this.style.cursor = 'pointer';
                    this.setAttribute('src', this.getAttribute('hsrc'));
               }	

               aImages[i].onmouseout = function() {
                    if (!sTempSrc) sTempSrc = this.getAttribute('src').replace('_o'+ftype, ftype);
                    this.setAttribute('src', sTempSrc);
               }
          }
     }
}

window.onload = initRollovers;