function getXMLHTTPRequest()
{
	try
	{
		req = new XMLHttpRequest();
	}
	catch(err1)
	{
	    try
	    {
	    	req = new ActiveXObject("Msxml2.XMLHTTP");
	    }
	    catch (err2)
	    {
	        try
	        {
	        	req = new ActiveXObject("Microsoft.XMLHTTP");
	        }
	        catch (err3)
	        {
	            req = false;
	        }
	    }
	}
	return req;
}

function queryAJAX(http, aUrl, callBack)
{
    myRand = parseInt(Math.random()*99999999999);
    myRandB = parseInt(Math.random());
    // add random number to URL to avoid cache problems
    var modurl = aUrl+"&rand="+myRand+"_"+myRandB;
    http.open("GET", modurl, true);
    // set up the callback function
    http.onreadystatechange = callBack;
    http.send(null);
}