function addLoadEvent(func) 
{
  var oldonload = window.onload;
  if (typeof window.onload != 'function') 
  {
    window.onload = func;
  } 
    else 
	{
	  window.onload = function() 
	  {
	    oldonload();
	    func();
 	  }
	}
  }

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";
 }
}

addLoadEvent(externalLinks);