function rolloverNav() {
if (!document.getElementsByTagName) return false;
if (!document.getElementById) return false;

var nav = document.getElementById("menu");
var images = nav.getElementsByTagName("img");

for(var i=0; i < images.length; i++) {
	images[i].onmouseover = function() {
		this.setAttribute("src", this.getAttribute("src").replace("_off.", "_on."));
	}

	images[i].onmouseout = function() {
		if (this.className != "current") {
		this.setAttribute("src", this.getAttribute("src").replace("_on.", "_off."));
		}
	}
}
}

if(window.addEventListener) {
	window.addEventListener("load", rolloverNav, false);
} else if(window.attachEvent) {
	window.attachEvent("onload", rolloverNav);
}