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";
}
}

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