AltovaXML 

AltovaXML is a FREE XML standards processor that includes the Altova XSLT 1.0 engine, XSLT 2.0 engine, XQuery engine, and XML validator. Now developers can use the same processors found in Altova XMLSpy 2005 in their own applications, free of charge.
xslt engine xquery engine standards processor xml validator

Chilkat Xml Parser Component 

Offers a high-performance alternative to the standard XML DOM for creating, navigating, and manipulating XML documents. The Chilkat XML parser is faster and less memory intensive, and the API is much simpler.
xml parser msxml dom sax com activex c++ visual basic delphi c++ builder