function plato(arg) {
  var rslt;
  if (document.getElementById) rslt = document.createElement('img');
  else rslt = new Image();
  rslt.src = arg;
  return rslt;
}
 
function changeImages() { 
  if (loadedjs && preloadFlag) { 
    for (var i=0; i<changeImages.arguments.length; i+=2) {
      document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
    }
  }
} 

function preloadImages() { 
  var imgFiles = preloadImages.arguments; 
  for (var i=0; i<imgFiles.length; i+=2) { 
    window[imgFiles[i]] = plato(imgFiles[i+1]);
    window[imgFiles[i]].src = imgFiles[i+1]; 
  } 
  preloadFlag = true; 
}

preloadImages('prehyperionhome',siteurl+'images/navigation/primary/hyperion_home_page_over.gif',
              'preonlinetech',siteurl+'images/navigation/primary/online_technical_support_over.gif',
              'prepartnerconnects',siteurl+'images/navigation/primary/partner_connections_over.gif',
              'precontactus',siteurl+'images/navigation/primary/contact_us_over.gif',
              'presitemap',siteurl+'images/navigation/primary/site_map_over.gif'
              ); 

var loadedjs = true;