function getXMLHTTPObject(){
    var xmlHttp;

    try {
        xmlHttp=new XMLHttpRequest();
    } catch (e) {
        try {
            xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e) {
            try {
                xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e) {
                // alert("Your browser does not support AJAX!");
                return false;
            }
        }
    }
    return xmlHttp;
}

function trackMe() {
    var xmlHttp = getXMLHTTPObject();
    xmlHttp.onreadystatechange=function() {
        if(xmlHttp.readyState==4) {
            var response=xmlHttp.responseText;
            alert(response);
        }
    }
    var data;

    data="appName="+ navigator.appName;
    data+="&appVersion="+ navigator.appVersion;
    data+="&appCodeName="+ navigator.appCodeName;
    data+="&platform="+ navigator.platform;
    data+="&oscpu="+ navigator.oscpu;
    data+="&cookieEnabled="+ navigator.cookieEnabled;
    data+="&language="+ navigator.language;
    data+="&vendor="+ navigator.vendorSub;
    data+="&vendorSub="+ navigator.vendor;
    data+="&product="+ navigator.product;
    data+="&productSub="+ navigator.productSub;
    data+="&res="+(window.screen.width+"x"+window.screen.height);
    data+="&url="+document.location.href;
    data+="&referrer="+document.referrer;
    data+="&uid=4bcc7d93e1b66";

    xmlHttp.open("GET","tracker.php?"+data,true);
    xmlHttp.send(null);

    //xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    //xmlHttp.setRequestHeader("Content-length", data.length);
    //xmlHttp.setRequestHeader("Connection", "close");
    alert(data);
    //xmlHttp.send(data);
}

server error log-
[Fri Apr 29 04:21:31 2011] [error] [client 117.199.154.173] File does not exist: /home/abhiguru/public_html/project/500.shtml, referer: /project.php
[Fri Apr 29 04:19:33 2011] [error] [client 117.199.154.173] File does not exist: /home/abhiguru/public_html/project/500.shtml, referer: /project.php
[Fri Apr 29 04:19:04 2011] [error] [client 117.199.154.173] File does not exist: /home/abhiguru/public_html/project/500.shtml, referer: /project.php