function toggleLayer(layerOne, layerTwo)
{
  var elem, vis;
  if( document.getElementById ) {// this is the way the standards work
    elem = document.getElementById(layerOne);
  }
  else if( document.all ) {// this is the way old msie versions work
      elem = document.all[layerOne];
  }
  else if( document.layers ){// this is the way nn4 works
    elem = document.layers[layerOne];
  }
  vis = elem.style;
  vis.display = 'none';
  document.getElementById(layerTwo).style.display = 'block';
  document.getElementById(layerTwo).style.visibility = 'visible';
}