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) //DOM method for binding an event (eg. FireFox)
window.addEventListener("load", externalLinks, false)

else if (window.attachEvent) //IE exclusive method for binding an event (eg. Internet Explorer)
window.attachEvent("onload", externalLinks)

else if (document.getElementById) //support older modern browsers
window.onload=externalLinks