function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}
function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}
var preloadFlag = false;
function preloadImages() {
	if (document.images) {	
	
		//Only the roll over images
		//Image URLs must be hard coded because default page is housed on a different server
		
		proj_over = newImage("http://project.pennera.upenn.edu/images/ERA/nav/project_over.gif");
		news_over = newImage("http://project.pennera.upenn.edu/images/ERA/nav/news_over.gif");
		links_over = newImage("http://project.pennera.upenn.edu/images/ERA/nav/links_over.gif");
		adv_over = newImage("http://project.pennera.upenn.edu/images/ERA/nav/adv_over.gif");
		logon_over = newImage("http://project.pennera.upenn.edu/images/ERA/nav/logon_over.gif");
		pennera_over = newImage("http://project.pennera.upenn.edu/images/ERA/nav/penners_over.gif");
		preloadFlag = true;
	}
}