function createXMLHTTP() 
{
	var ajax;

	try 
	{
		ajax = new ActiveXObject("Microsoft.XMLHTTP");
	} 
	catch(e) 
	{
		try 
		{
			ajax = new ActiveXObject("Msxml2.XMLHTTP");
			alert(ajax);
		}
		catch(ex) 
		{
			try 
			{
				ajax = new XMLHttpRequest();
			}
			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.");
}