var rolloverInitialized = false;
function rolloverInit() {

   if (!rolloverInitialized) {
	   
	   var large_image_id = document.getElementById("big").getElementsByTagName('img')[0];

	  // get all images
      var images 	= new Array();
         images 	= document.getElementById("thumbs").getElementsByTagName('img');
      
      // get all images with unique_id in src value
      for (var i = 0; i < images.length; i++) {

            var image = images[i];
            
            // store the off state filename in a property of the image object
            image.offImage = new Image();
            image.offImage.src = image.src;
            
            // store the on state filename in a property of the image object
            // (also preloads the rollover state image!)
            image.onImage = new Image();
            image.onImage.imageElement = image;
            
            // add onmouseover and onmouseout event handlers once the on state image has loaded
            // Safari's onload is screwed up for off-screen images; temporary fix
            if (navigator.userAgent.toLowerCase().indexOf('safari') != - 1) {
               image.onmouseover = function() {
                  large_image_id.src = this.onImage.src;
               };
            }
            else {
               image.onImage.onload = function() {
                  this.imageElement.onmouseover = function() {
                     large_image_id.src = this.onImage.src;
                  };
               };
            }
            
            // set src of on state image after defining onload event handler
            image.onImage.src = image.src;

      }
   }
   rolloverInitialized = true;
}

// call rolloverInit when document finishes loading
if (window.addEventListener) {
   window.addEventListener('load', rolloverInit, false);
}
else if (window.attachEvent) {
   window.attachEvent('onload', rolloverInit);
}