function GetXmlHttpObject()
{
var xmlHttp = null;
if (window.XMLHttpRequest) { // Mozilla, Safari, ...
            xmlHttp = new XMLHttpRequest();
            if (xmlHttp.overrideMimeType) {
                xmlHttp.overrideMimeType('text/xml');
                // See note below about this line
            }
        } 
        else if (window.ActiveXObject) { // IE
            try {
                xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
            } 
            catch (e) {
                try {
                    xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
                } 
                catch (e) {}
            }
        }
return xmlHttp;
}