I've been looking for a simple XML Editor for a while and have tried the all the usual ones, but now I have discovered Liquid Technologies XML Editor. Its very easy to use (free) as part of the XML Studio Community Edition (which also has some excellent tools - XML Schema Editor)
It has all the main features - Intellisense, Validation, XML Differencing, converts XML to XSD, formatting, Auto Complete, XPath query viewer.......
