function initRollover()
{
 var imgs = $A($$('img.mouseovers'));
 imgs.each(function(img){
  Event.observe(img,'mouseover',
   function(){
    var suffix = img.src.substring(img.src.lastIndexOf ('.'));
    img.src = img.src.substring(0,img.src.lastIndexOf('.')) + "-over" + suffix;
   },
   false
  );
  Event.observe(img,'mouseout',
   function(){
    img.src = img.src.replace("-over","");
   },
   false
  );
 });

}

Event.observe(window, 'load', initRollover, false);