function newImage( imgSrc )  {

 var imgName = new Image();
 imgName.src = imgSrc;

 return imgName;
}

function change( imgName, imgLocation )  {
  document[imgName].src = imgLocation;
}

var preloadFlag = false;

function loadImages()  {
  if (document.images)  {
    home_over = newImage("/image/homeNav_over.gif");
    services_over = newImage("/image/servicesNav_over.gif");
    clients_over = newImage("/image/clientsNav_over.gif");
    //principals_over = newImage("/image/principalsNav_over.gif");
    capability_over = newImage("/image/capabilityNav_over.gif");
    hiring_over = newImage("/image/hiringNav_over.gif");

    preloadFlag = true;
  }
}

function changeNav(nav, over)  {
  var imgName;
  var imgLocation = "/image/";

  imgName = nav + "Nav";
  imgLocation += imgName;

  if(over == 1)  {
    imgLocation += "_over";
  }

  imgLocation += ".jpg";

  change(imgName, imgLocation);
}