function preload(imgName) {
	var moimg = new Image();
	moimg.src = "images/" + imgName + "2.gif";
}

function dnImg(imgName) {
	document.images[imgName].src = "images/" + imgName + "2.gif";
}

function upImg(imgName) {
	document.images[imgName].src = "images/" + imgName + ".gif";
}