This version has both the 2005 and 2008 solutions.  The initial post was a 2008 only solution.  Sorry

StrataFrame has an XmlBasics class that helps in the creation, opening, encryption, and writing of Xml files.  One of these features also includes the ability to use a validation key which can be an added level of encryption.  An example use of this would be to use a has that has a checksum of the hardware on the computer or a MAC address to prevent an XML file from simply being copied to another computer for another user to take advantage of.  This sample show how to use the validation key as part of the XmlBasics class.