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) {
		bt_history_over = newImage("../images/bt_history_over.gif");
		bt_challenge_over = newImage("../images/bt_challenge_over.gif");
		bt_blog_over = newImage("../images/bt_blog_over.gif");
		bt_forum_e_over = newImage("../images/bt_forum_e_over.gif");
		bt_pictures_over = newImage("../images/bt_pictures_over.gif");
		bt_videos_e_over = newImage("../images/bt_videos_e_over.gif");
		bt_participate_over = newImage("../images/bt_participate_over.gif");
		bt_partners_over = newImage("../images/bt_partners_over.gif");
		bt_about_over = newImage("../images/bt_about_over.gif");
		bt_pressroom_over = newImage("../images/bt_pressroom_over.gif");
		preloadFlag = true;
	}
}