function externalLinks() {
	if (!document.getElementsByTagName) return;
 	var anchors = document.getElementsByTagName('a');
	for (var i=0; i<anchors.length; i++) {
   		anchor = anchors[i];			
		var rel = anchor.rel;			
		if (anchor.getAttribute('href') && rel.substring(0,8) == 'external' )
			anchor.target = '_blank';			
 	}			
}

if (window.addEventListener)
	window.addEventListener("load", externalLinks, false)
else if (window.attachEvent)
	window.attachEvent("onload", externalLinks)
else if (document.getElementById)
	window.onload=externalLinks