var activeNav = -1;
var switchToNav = function highlightNav(e, which) {
  switchNav(which);
}

var switchNav = function highlightNavStep1(which) {
  if (which == activeNav) {
    return;
  }
  priorNav = activeNav;
  activeNav = parseInt(which);
  if (activeNav > -1) {
    YAHOO.util.Dom.setStyle('secondnav' + priorNav, 'display', 'none'); 
    YAHOO.util.Dom.setStyle('secondnav' + activeNav, 'display', 'block'); 
  } else {
    YAHOO.util.Dom.setStyle('secondnav' + activeNav, 'display', 'block'); 
  }
}

YAHOO.util.Event.on('nav1', 'mouseover', switchToNav, '1');
YAHOO.util.Event.on('nav2', 'mouseover', switchToNav, '2');
YAHOO.util.Event.on('nav3', 'mouseover', switchToNav, '3');
YAHOO.util.Event.on('nav4', 'mouseover', switchToNav, '4');
YAHOO.util.Event.on('nav5', 'mouseover', switchToNav, '5');
YAHOO.util.Event.on('nav6', 'mouseover', switchToNav, '6');