function init() {

	externalLinks()

	var nav		= document.getElementById('nav');
	var urls	= nav.getElementsByTagName('a');

	for (var i = 0; i < urls.length; i++) {

		if (urls[i].href != window.location) {
	
			urls[i].onmouseover = function() {
				var img = this.getElementsByTagName('img')[0];
				var src = img.src;
				src = src.substr(0, src.indexOf('.gif'));
				src = src + '_hover.gif';
				img.src = src;
			}

			urls[i].onmouseout = function() {
				var img = this.getElementsByTagName('img')[0];
				var src = img.src;
				src = src.substr(0, src.indexOf('_hover.gif'));
				src = src + '.gif';
				img.src = src;
			}
		}
	}
}

function externalLinks() {
 if (!document.getElementsByTagName) return;
 var anchors = document.getElementsByTagName("a");
 for (var i=0; i<anchors.length; i++) {
   var anchor = anchors[i];
   if (anchor.getAttribute("href") &&
       anchor.getAttribute("rel") == "external")
     anchor.target = "_blank";
 }
}
window.onload = init();