XPathVisualizer is a simple, free Winforms tool to help you visualize
the results of XPath queries on XML documents.
—- Comment from its home page
Home page : http://xpathvisualizer.codeplex.com/
Download page : http://xpathvisualizer.codeplex.com/releases/view/76656
What I found it is better that is you can add the prefix as many as possible.
And you don’t need to click Test! each time, it will detect automaticlly.
It will also highlight the result matched.
Bref, I think that it is a good tool, so share with you !