function navOver(n)
  {
  document.images[n].src          = "images/nav/" + n + "_on.gif";
  document.images[n + '_txt'].src = "images/nav/" + n + "_txt.gif";
  }

function navOut(n)
  {
  document.images[n].src          = "images/nav/" + n + ".gif";
  document.images[n + '_txt'].src = "images/spacer.gif";
  }