var bannerIndex = -1;
var maxBannerIndex = 2;

//var bannerHandler = setInterval("rotateBanner()",2000);

function rotateBanner() {
  hideLayer("banner_" + bannerIndex);
  bannerIndex = (bannerIndex==maxBannerIndex)?0:bannerIndex+1;
  showLayer("banner_" + bannerIndex);
}


function hideLayer(whichLayer) { 
 if (document.getElementById) { 
    if (document.getElementById(whichLayer) != null) {
      document.getElementById(whichLayer).style.visibility = "hidden"; 
    }
  } else if (document.all) { 
    document.all[whichlayer].style.visibility = "hidden"; 
  } else if (document.layers) { 
    document.layers[whichLayer].visibility = "hidden"; 
  }  
} 
 
function showLayer(whichLayer) { 
  if (document.getElementById) { 
    if (document.getElementById(whichLayer) != null) {
      document.getElementById(whichLayer).style.visibility = "visible"; 
    }
  } else if (document.all) { 
    document.all[whichlayer].style.visibility = "visible"; 
  } else if (document.layers) { 
    document.layers[whichLayer].visibility = "visible";
  } 
}