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";
     anchor.onclick = openInNewWindow;
 }
}
window.onload = externalLinks;

function openInNewWindow() {
	var newWindow = window.open(this.getAttribute('href'), '_blank','width=600','height=400');
	newWindow.focus();
	return false;
}