function getRequestObject ()
{
        try
        {
                // Firefox, Opera 8.0+, Safari
                return new XMLHttpRequest();
        }
        catch (e)
        {
                // Internet Explorer
                try
                {
                        return new ActiveXObject("Msxml2.XMLHTTP");
                }
                catch (e)
                {
                        try
                        {
                                return new ActiveXObject("Microsoft.XMLHTTP");
                        }
                        catch (e)
                        {
                                alert ("Your browser cannot support AJAX!");
                                return null;
                        }
                }
        }
}