function initTopNav()
{
	var btns = $('topNav').getElements('img');
	
	for (var i = 0; i < btns.length; i++) {
		var tempArr = btns[i].src.split('.gif');
		var name = tempArr[0];
		if (name.indexOf('_on') == -1) {
			btns[i].rollOn = name + "_over.gif";
			btns[i].rollOut = name + ".gif";
			btns[i].addEvent('mouseover', function(e){
				e = new Event(e);
				this.src = this.rollOn;
				e.stop();
			});
			btns[i].addEvent('mouseout', function(e){
				e = new Event(e);
				this.src = this.rollOut;
				e.stop();
			});
		}
	}
}

window.addEvent('domready', initTopNav);