function highlightNavItem(item) {
  var newURL='../images/nav/red/' + item + '.gif';
  var imageName = 'document.' + item;
  var imageObject = eval(imageName);
  imageObject.src = newURL;
  }

function lowlightNavItem(item) {
  var newURL='../images/nav/black/' + item + '.gif';
  var imageName = 'document.' + item;
  var imageObject = eval(imageName);
  imageObject.src = newURL;
}