function createRequestObject()
{
   if (window.XMLHttpRequest) 
   {
      try 
      {
           // Mozilla, Safari, ...
           return new XMLHttpRequest();
       } 
       catch (e){}
   } 
   else 
       if (window.ActiveXObject) 
       {
          try 
          {
              //old IE
              return new ActiveXObject('Msxml2.XMLHTTP');
          } 
          catch (e){}
          try 
          {
               //IE
               return new ActiveXObject('Microsoft.XMLHTTP');
          } 
          catch (e){}
       }
    return null; 
}