function makeHttpRequest(url, callback_function, return_xml) { 
    var http_request = false; 

    if (window.XMLHttpRequest) { // Mozilla, Safari,... 
        http_request = new XMLHttpRequest(); 
        if (http_request.overrideMimeType) { 
            http_request.overrideMimeType('text/xml'); 
        } 
    } else if (window.ActiveXObject) { // IE 
        try { 
            http_request = new ActiveXObject("Msxml2.XMLHTTP"); 
        } catch (e) { 
            try { 
                http_request = new ActiveXObject("Microsoft.XMLHTTP"); 
            } catch (e) {} 
        } 
    } 

    if (!http_request) { 
        alert('Unfortunatelly you browser doesn\'t support this feature.'); 
        return false; 
    } 
    http_request.onreadystatechange = function() { 
        if (http_request.readyState == 4) { 
            if (http_request.status == 200) { 
                if (return_xml) { 
                    eval(callback_function + '(http_request.responseXML)'); 
                } else { 
                    eval(callback_function + '(http_request.responseText)'); 
                } 
            } else { 
                alert('There was a problem with the request.(Code: ' + http_request.status + ')'); 
            } 
        } 
    } 
    http_request.open('GET', url, true); 
    http_request.send(null); 
}