$(document).ready(function() {
	$(".rollover").hover(
	 function() {
	  curr = $(this).attr('src');
		ext = curr.substr(curr.lastIndexOf('.'),4);
	  overlen = curr.length;
	  over = curr.substr(0, overlen-4);
	  over = over+'_o'+ext;
	  $(this).attr({ src: over});
	 },
	 function() {
    if (typeof curr !== 'undefined') {
       $(this).attr({ src: curr});
    }
	 }
	)

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