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) {
		id20_over = newImage("images/20-over.gif");
		id21_over = newImage("images/21-over.gif");
		id22_over = newImage("images/22-over.gif");
		id23_over = newImage("images/23-over.gif");
		id24_over = newImage("images/24-over.gif");
		id25_over = newImage("images/25-over.gif");
		id28_over = newImage("images/28-over.gif");
		preloadFlag = true;
	}
}