Our server uses an old version of MSXML. Will this be a problem?

Most Windows servers will have an old version of MSXML. This won't be a problem, as long as you use the following progids:

Microsoft.XMLDOM, Microsoft.XMLHTTP		MSXML 1.x and MSXML 2.x, MSXML 3.0 in replace mode.
MSXML2.DOMDocument, MSXML2.XMLHTTP		MSXML 2.x and MSXML 3.0 in replace mode.
MSXML2.DOMDocument.3.0, MSXML2.XMLHTTP.3.0		MSXML 3.0 only

Make sure you don't mix these (i.e., MSXML2.DOMDocument.3.0 and MSXML2.XMLHTTP - this will only work for MSXML 3.0 in replace mode).