For those who do not know yet, the XML integration with the DataSet is very powerful. Most of the integration is about filling and getting XML from your DataSet. But the XmlDataDocument is really cool. Simply by assigning the DataSet to the XmlDataDocument, you can work with the DataSet data either relationally (through the DataSet) or hierarchically (through the XmlDocument). So, next time you need to transform the DataSet data or just run an XPath query, assign your DataSet to an XmlDataDocument and watch the magic begin...