function createXMLHTTP() 
{
	var ajax;
	try 
	{
		ajax = new ActiveXObject("Microsoft.XMLHTTP");
		return ajax;
        }
	catch(e) 
	{
		try 
		{
			ajax = new ActiveXObject("Msxml2.XMLHTTP");
			return ajax;
		}
		catch(ex) 
		{
			try 
			{
				ajax = new XMLHttpRequest();
				return ajax;
			}
			catch(exc) 
			{
				alert("Esse browser não tem recursos para uso do Ajax");
				ajax = null;
			}
		}
//		return ajax;
	}

	var arrSignatures = ["MSXML2.XMLHTTP.5.0", "MSXML2.XMLHTTP.4.0", "MSXML2.XMLHTTP.3.0", "MSXML2.XMLHTTP", "Microsoft.XMLHTTP"];
	for (var i=0; i < arrSignatures.length; i++)
	{
		try 
		{
			var oRequest = new ActiveXObject(arrSignatures[i]);
			return oRequest;
		} 
		catch (oError) 
                {
		}
	}
        
	throw new Error("MSXML is not installed on your system.");	

}