var popheight=520;
  var popwidth=500;

  function openSWindow(pageToLoad, winName, center) {
  xposition=0; yposition=0;
  if ((parseInt(navigator.appVersion) >= 4 ) && (center)){
  xposition = (screen.width - popwidth) / 2;
  if (xposition < 280) xposition = 280;
  yposition = (screen.height - popheight) / 2;
  }
  args = "width=" + popwidth + ","
    + "location=0,"
    + "menubar=0,"
    + "resizable=0,"
    + "status=0,"
    + "titlebar=0,"
    + "toolbar=0,"
    + "height=" + popheight + ","
    + "screenx=" + xposition + ","  //NN
    + "screeny=" + yposition + ","  //NN
    + "left=" + xposition + ","    //IE
    + "top=" + yposition;          //IE
  var popwin=window.open(pageToLoad,winName,args);
 popwin.focus();
 }