function myPreloadImages() { 
  hiImg = new Image(11,17);
  hiImg.src = "/pic/top-menu/top-arrow-hi.gif";
  offImg = new Image(11,17);
  offImg.src = "/pic/top-menu/top-arrow.gif";
}

function mySwapArrow( menuNum) {
  if ((document.images) && (offImg != null)) {
    document.images["ImgArrow_" + menuNum].src = hiImg.src;
  }
}

function myRestoreArrow( menuNum) {
  if ((document.images) && (offImg != null)) {
    document.images["ImgArrow_" + menuNum].src = offImg.src;
  }
}