var pl = new Array();
function doPreload() {
    for (var j=0; j < arguments.length; j++) {
        pl[j] = document.createElement('img');
        pl[j].setAttribute( 'src', arguments[j] );
    }
}

Event.observe(window, 'load', function () {
   if (Prototype.Browser.IE) {
      $$('#nav li').each(function(el) {
         el.onmouseover = function() { el.className += ' hover'; }
         el.onmouseout = function() { el.className = el.removeClassName('hover'); }
      });
   }
});