function GetXMLHttp() {

var xmlHttp;
try {
xmlHttp = new XMLHttpRequest();
}
catch(ee) {
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
}
catch(e) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
catch(e) {
xmlHttp = false;
}
}
}
return xmlHttp;
}

var xmlRequest = GetXMLHttp();