function popup(url,name,width,height,resize,scroll) {
 var dialogWin = new Object();
 dialogWin.width = width;
 dialogWin.height = height;
 now = new Date();
 var millis=now.getTime();
 var mstr=""+millis;
 if (navigator.appName == "Netscape") {
  dialogWin.left = window.screenX + ((window.outerWidth - dialogWin.width) / 2);
  dialogWin.top = window.screenY + ((window.outerHeight - dialogWin.height) / 2);
  var attr = 'screenX=' + dialogWin.left + ',screenY=' + dialogWin.top + ',resizable=' + resize + ',width=' + dialogWin.width + ',height=' + dialogWin.height + ',scrollbars=' + scroll + ',menubar=no,location=no,toolbar=no,status=no,directories=no';
 } else if (document.all) {                                         
  dialogWin.left = (screen.width - dialogWin.width) / 2;
  dialogWin.top = (screen.height - dialogWin.height) / 2;
  var attr = 'left=' + dialogWin.left + ',top=' + dialogWin.top + ',resizable=' + resize + ',width=' + dialogWin.width + ',height=' + dialogWin.height + ',scrollbars=' + scroll + ',menubar=no,location=no,toolbar=no,status=no,directories=no';
 }
 // AGREGA EL CODIGO ANTI-CACHING
 tienesp=false;
 for (i=0; i<url.length; i++)
 if (url.charAt(i)=='?')
  tienesp=true;
 if (tienesp)
  nocach='&nocache='+mstr;
 else
  nocach='?nocache='+mstr;
  window.open(url + nocach ,name,attr);
}