function switchLayers( layerName ) {
      if ( document.getElementById ) {
        var layerSiteBuilder = document.getElementById( 'layerSiteBuilder' );
        var layerEmail = document.getElementById( 'layerEmail' );
        var layerWebStats = document.getElementById( 'layerWebStats' );
        var layerWebSpace = document.getElementById( 'layerWebSpace' );
        var layerWebTools = document.getElementById( 'layerWebTools' );

        layerSiteBuilder.style.display = 'none';
        layerEmail.style.display = 'none';
        layerWebStats.style.display = 'none';
        layerWebSpace.style.display = 'none';
        layerWebTools.style.display = 'none';
        
        switch(layerName) {

            case "layerSiteBuilder":
            layerSiteBuilder.style.display = 'block';
            break;
     
            case "layerEmail":
            layerEmail.style.display = 'block';
            break;
     
            case "layerWebStats":
            layerWebStats.style.display = 'block';
            break;
          
            case "layerWebSpace":
            layerWebSpace.style.display = 'block';
            break;


            case "layerWebTools":
            layerWebTools.style.display = 'block';
            break;

            default:
            break;
        }
      }
    }
    switchLayers('layerEmail');