function imageSwap(id) {
	var links = document.getElementById(id).getElementsByTagName("a");
	var imgLoad = []

	for(var i = 0; i < links.length; i++) {
		attachBehavior(links[i], i);
	}

	function attachBehavior(obj, iter) {
		
		var img = obj.getElementsByTagName('img')[0];
		var imgSrc = img.getAttribute("src");
		var ext = imgSrc.match(/\.\S{3}$/);
		var overSrc = imgSrc.replace(ext, "-hl" + ext);
		
                       // preLoad over states
		imgLoad[iter] = new Image();
		imgLoad[iter].src = overSrc
		
                       // use event listeners if appropriate
		obj.onmouseover = function(){
			img.setAttribute("src", overSrc);
		}
		obj.onmouseout = function(){
			img.setAttribute("src", imgSrc);
		}
	}
}