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) {
		nav_home_over = newImage("images/nav_home-over.gif");
		nav_about_over = newImage("images/nav_about-over.gif");
		nav_case_over = newImage("images/nav_case-over.gif");
		nav_publications_over = newImage("images/nav_publications-over.gif");
		nav_links_over = newImage("images/nav_links-over.gif");
		nav_contactus_over = newImage("images/nav_contactus-over.gif");
		nav_news_over = newImage("images/nav_news-over.gif");
		nav_member_over = newImage("images/nav_member-over.gif");
		preloadFlag = true;
	}
}