function menuInit() {
	$$('img').each(function(img) {
		if (img.src.indexOf("menu") != -1) {
			var imgSrc = img.src;
			var lastDotPos = imgSrc.lastIndexOf(".");
			var imgName = imgSrc.substring(0, lastDotPos);
			var imgExt = imgSrc.substring(lastDotPos + 1);
			var overSrc = imgName + "_o." + imgExt;
			var overImg = new Image(); overImg.src = overSrc;
			img.addEvent('mouseover', menuSwap.bindAsEventListener(img, overSrc));
			img.addEvent('mouseout', menuSwap.bindAsEventListener(img, imgSrc));
		}
	});
}

function menuSwap(evt, src) {
	if (this.src != src)
		this.src = src;
}

window.addEvent('domready', menuInit);