var xmlhttp = false;

try{
	xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch(e){
	try{ xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e){ xmlhttp = false; }
}

if (!xmlhttp && typeof XMLHttpRequest != 'undefined'){
	try{ xmlhttp = new XMLHttpRequest(); } catch (e){ xmlhttp = false; }
}

if (!xmlhttp && window.createRequest){
	try{ xmlhttp = window.createRequest(); } catch (e){ xmlhttp = false; }
}