var preloadImgs = new Array();

Event.observe(window, 'load', focusBox, false);
function focusBox() {
  obj = document.getElementsByClassName('focusbox');
  obj.each(function (node){
    node.onfocus = function() { this.className = 'focusbox on'; }
    node.onblur = function() { this.className = 'focusbox'; }
  });
}

Event.observe(window, 'load', rollover, false);
function rollover() {
  obj = $A(document.getElementsByClassName('rollover'));
  obj.each(function (node){
    node.imgsrc = node.src;
    node.imgext = node.imgsrc.substring(node.imgsrc.lastIndexOf('.'), node.imgsrc.length);
    node.imgsrc_o = node.imgsrc.replace(node.imgext, '_o'+node.imgext);
    node.onmouseover = function() { this.src = this.imgsrc_o; };
    node.onmouseout = function() { this.src = this.imgsrc; };
    var i = preloadImgs.length;
    preloadImgs[i] = new Image();
    preloadImgs[i].src = node.imgsrc_o;
  });
}