if (document.images) {
   homeOn = new Image();
   homeOn.src = "/images/header/nav/home_on.gif";
   aboutOn = new Image();
   aboutOn.src = "/images/header/nav/about_on.gif";
   servicesOn = new Image();
   servicesOn.src = "/images/header/nav/services_on.gif";
   casestudiesOn = new Image();
   casestudiesOn.src = "/images/header/nav/casestudies_on.gif";
   newsOn = new Image();
   newsOn.src = "/images/header/nav/news_on.gif";
   contactOn = new Image();
   contactOn.src = "/images/header/nav/contact_on.gif";
   
   homeOff = new Image();
   homeOff.src = "/images/header/nav/home_off.gif";
   aboutOff = new Image();
   aboutOff.src = "/images/header/nav/about_off.gif";
   servicesOff = new Image();
   servicesOff.src = "/images/header/nav/services_off.gif";
   casestudiesOff = new Image();
   casestudiesOff.src = "/images/header/nav/casestudies_off.gif";
   newsOff = new Image();
   newsOff.src = "/images/header/nav/news_off.gif";
   contactOff = new Image();
   contactOff.src = "/images/header/nav/contact_off.gif";
   
}


function swapImage(imgName,newImage) {
   if (document.images) {
      eval('document.' + imgName + '.src = ' + newImage + '.src');
   }
}