$(document).ready(function(){
$(".rollover").hover(
 function() {
  curr = $(this).find("img").attr("src");
  overlen = curr.length;
  over = curr.substr(0, overlen-4);
  over = over+'-ro.jpg';
  $(this).find("img").attr({ src: over});
 },
 function() {
  $(this).find("img").attr({ src: curr});
 }
)

$(".rollover").find("img").each(function(i) {
  temp = this.src;
  prelen = temp.length;
  pre = temp.substr(0, prelen-4);
  pre = pre+'-ro.jpg';
  preload_image_object = new Image();
  preload_image_object.src = pre;
});
});