// Sergi Meseguer - www.zigotica.com
var POPUP = {   
   open : function(a,where,args) {
            a.onclick = function(){
               window.open( where, '', args);
               return false;
            }     
   },

   init : function() {
      var external = document.links;
      for (var k=0; k<external.length; k++){
         if (external[k].href && external[k].className && external[k].className.indexOf('popup') != -1) {
       if(external[k].className == "popup") external[k].target = "_blank";
       else {
          var argumentos = external[k].className.substring(6);
               POPUP.open(external[k],external[k].href,argumentos);
       }
         }
      }
   }
}
// we recommend using an onload event as in
// http://simon.incutio.com/archive/2004/05/26/addLoadEvent
window.onload = POPUP.init;