How do I found out the server name and class of *any* registered automation server?

For example, I have two versions of XMLDOM registered: MSXML.DLL and MSXML3.DLL. WWXML only finds the OLDER (and buggy) one when it executes CREATEOBJECT("Microsoft.xmldom"). I have found I can use Microsoft's XMLINST.EXE to change all the classids, but this may corrupt a prior program that expects the older classid.