function open_window(url, popW, popH, scroll, resize) {
  var w = 480, h = 340;
  if (document.all || document.layers) {
    w = screen.availWidth;
    h = screen.availHeight;
  }
  
  var leftPos = (w-popW)/2, topPos = (h-popH)/2;
  myWindow = window.open(url,'popup','width=' + popW + ',height=' + popH + ',top=' + topPos + ',left=' + leftPos + ',toolbar=no,menubar=no,status=no,scrollbars='+scroll+',resizable='+resize);
  myWindow.resizeTo(popW,popH);
  myWindow.focus();
}