function switchDiv(chkbox, div_id) {

  var style_sheet = getStyleObject(div_id);

  if (style_sheet) {

    var visSetting = (chkbox.checked) ? "visible" : "hidden"
    document.getElementById(div_id).style.visibility = visSetting

  }

}

function getStyleObject(objectId) {
  // checkW3C DOM, then MSIE 4, then NN 4.
  //
  if(document.getElementById && document.getElementById(objectId)) {
        return document.getElementById(objectId).style;
   }
   else if (document.all && document.all(objectId)) {  
        return document.all(objectId).style;
   } 
   else if (document.layers && document.layers[objectId]) { 
        return document.layers[objectId];
   } else {
        return false;
   }
}

function changeObjectVisibility(objectId, newVisibility) {
    // first get the object's stylesheet
    var styleObject = getStyleObject(objectId);

    // then if we find a stylesheet, set its visibility
    // as requested
    //
    if (styleObject) {
        styleObject.visibility = newVisibility;
        return true;
    } else {
        return false;
    }
}