@thomas.schmidt: Thank you for the feedback.
Your experience with "WinHTTP.WinHTTPRequest.5.1" is interesting. The information I can find suggests that "MSXML2.ServerXMLHTTP" is the right object for servers. See: http://msdn.microsoft.com/en-us/library/ms762278(v=VS.85).aspx
I'm not arguing your experience, and there could have been / could be a bug of which I am not aware.
The ServerXMLHTTP object offers functionality similar to that of the XMLHTTP object. Unlike XMLHTTP, however, the ServerXMLHTTP object does not rely on the WinInet control for HTTP access to remote XML documents. ServerXMLHTTP uses a new HTTP client stack. Designed for server applications, this server-safe subset of WinInet offers the following advantages...