var imagesLoaded = false;

   function preLoadImages(){
     var images = new Array('images/menuHomeOver.gif','images/menuServicesOver.gif','images/menuProjectsOver.gif','images/menuOurTeamOver.gif','images/menuNewsOver.gif','images/menuContactUsOver.gif');

     for(loop = 0; loop<images.length; loop++){
       var image = new Image();
       image.src = images[loop];
     }

   imagesLoaded = true;

   }

   preLoadImages();

   function swapImage(){
     if (imagesLoaded) {
       document[swapImage.arguments[0]].src = [swapImage.arguments[1]];
     }
   }