function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}
var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		menu11 = newImage("image/menu11.gif");
		menu21 = newImage("image/menu21.gif");
		menu31 = newImage("image/menu31.gif");
		menu42 = newImage("image/menu42.gif");
		preloadFlag = true;
	}
}
function changeImages(imgName,fileName) {
	if (document.images && (preloadFlag == true)) {
		document.images[imgName].src = fileName;
	}
}