the crxml parser is a real easy to parser.
This class has got a search function, which takes a node name with any namespace as an argument. It searches the xml for the node and prints out the access statement to access that node using this class. This class also makes xml generation very easy.
you can download this class at
http://freshmeat.net/projects/crxml
or from phpclasses.org
http://www.phpclasses.org/package/6769-PHP-Manipulate-XML-documents-as-array.html