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";
 }
}

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