var offSrc="";
var onImg = "";
var offSrc = "";

function roll(vImg,vSrc) {
	vSrc = "img/nav-"+vImg.name+"-hi.gif";
	offSrc = vImg.src;
	onImg = vImg;
	vImg.src = vSrc;
}

function rollOff() {
	onImg.src=offSrc;
}