function checkOS() {

  if(navigator.userAgent.indexOf('Linux') != -1){
     var OpSys = "LINUX BOX";
  }
  else{
     if((navigator.userAgent.indexOf('Win') != -1) &&
          (navigator.userAgent.indexOf('95') != -1)){
        var OpSys = "PC";
     }
     else{
        if((navigator.userAgent.indexOf('Win') != -1) &&
          (navigator.userAgent.indexOf('98') != -1)){
        var OpSys = "PC";
        }
        else{
           if(navigator.userAgent.indexOf('Win') != -1){
              var OpSys = "PC";
           }
           else{
              if(navigator.userAgent.indexOf('Mac') != -1){
                 var OpSys = "MAC";
              }
              else{
				  // unknown, assume non computer
                 var OpSys = "DEVICE";
              }
           }
        }
     }
  }
  document.write(OpSys);
}