function initRollOverImages() {

  var image_cache = new Object();

  $("img.hover").each(function(i) {

    var imgsrc = this.src;

    var dot = this.src.lastIndexOf('.');

    var imgsrc_on = this.src.substr(0, dot) + '_on' + this.src.substr(dot, 4);

    image_cache[this.src] = new Image();

    image_cache[this.src].src = imgsrc_on;

    $(this).hover(

      function() { this.src = imgsrc_on; },

      function() { this.src = imgsrc; });

  });

}



$(document).ready(initRollOverImages);