XML to XSD

[Adam Greene]

Does anyone know of a good (and free) program that would help one create an XML Schema from an XML file.  I'm still kind of new to all these different XML formats (DTD, XML, XSD, WSDL, and the list goes on), but I want to use Castor to create classes for loading and saving XML and it wants to start with an XSD.  Or as a another possibility an XML to Java maker / compiler.  Does Xerces have one (like Xalan has the XSLT compiler)??