jQuery.preloadImages = function()
{
  for(var i = 0; i<arguments.length; i++)
  {
    jQuery("<img>").attr("src", arguments[i]);
  }
}
$.preloadImages("/files/H&Wrollover2.jpg", "/files/GLrollover.jpg","/files/CBrollover.jpg");

$(document).ready(function(){
  $("#dirHW").mouseover(function() {
    this.src = '/files/H&Wrollover2.jpg';
  }).mouseout(function(){
    this.src = '/images/nl-H&W.gif';
  });
  $("#dirGL").mouseover(function() {
    this.src = '/files/GLrollover.jpg';
  }).mouseout(function(){
    this.src = '/images/nl-GL.gif';
  });
  $("#dirCB").mouseover(function() {
    this.src = '/files/CBrollover.jpg';
  }).mouseout(function(){
    this.src = '/images/nl-CB.gif';
  });
});