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) {
		wel_over = newImage("images/wel-over.gif");
		abo_over = newImage("images/abo-over.gif");
		edu_over = newImage("images/edu-over.gif");
		you_over = newImage("images/you-over.gif");
		gro_over = newImage("images/gro-over.gif");
		min_over = newImage("images/min-over.gif");
		res_over = newImage("images/res-over.gif");
		preloadFlag = true;
	}
}