var xmlHttp;  
var is_ie = (navigator.userAgent.indexOf('MSIE') >= 0) ? 1 : 0; 
var is_ie5 = (navigator.appVersion.indexOf("MSIE 5.5")!=-1) ? 1 : 0; 
var is_opera = ((navigator.userAgent.indexOf("Opera6")!=-1)||(navigator.userAgent.indexOf("Opera/6")!=-1)) ? 1 : 0; 
var is_netscape = (navigator.userAgent.indexOf('Netscape') >= 0) ? 1 : 0; 

function XmlHttp_Get(xmlhttp, url) { 
    xmlhttp.open('GET', url, true); 
    xmlhttp.send(null); 
} 

function GetXmlHttpObject(handler) { 
    var objXmlHttp = null;
    
    if (is_ie){ 
        var strObjName = (is_ie5) ? 'Microsoft.XMLHTTP' : 'Msxml2.XMLHTTP'; 
            
        try { 
            objXmlHttp = new ActiveXObject(strObjName); 
            objXmlHttp.onreadystatechange = handler; 
        } catch(e) { 
            alert('IE detected, but object could not be created. Verify that active scripting and activeX controls are enabled'); 
            return; 
        } 
    } else if (is_opera) { 
        alert('Opera detected. The page may not behave as expected.'); 
        return; 
    } else { 
        // Mozilla | Netscape | Safari 
        objXmlHttp = new XMLHttpRequest(); 
        objXmlHttp.onload = handler; 
        objXmlHttp.onerror = handler; 
    } 
    return objXmlHttp; 
}