function addNavRollovers() {
	
	var imgCache = new Array();
	var nav = document.getElementById('nav');
	var imgs = nav.getElementsByTagName('img');
	for (var i=0;i<imgs.length;i++)
	{
		imgCache[i] = new Image();
		imgCache[i].src = 'images/' + imgs[i].id + '_on.gif';
		imgs[i].onmouseover = rolloverOn;
		imgs[i].onmouseout = rolloverOff;
	}
	
}

function rolloverOn() {
	this.src = 'images/' + this.id + '_on.gif'
}


function rolloverOff(elem) {
	this.src = 'images/' + this.id + '.gif'
}