browserName = navigator.appName;
browserVer = parseInt(navigator.appVersion);
ns3up = (browserName == "Netscape" && browserVer >= 3);
ie4up = (browserName.indexOf("Microsoft") >= 0 && browserVer >= 4);
if (ns3up || ie4up){
    document.write( screen.width + 'x' + screen.height);
  }