Ed, I search for tools like we discussed last night but everything I found was either a commercial product, poorly rated or dated. I tried 2 of the but one would not run and the other was a Windows product despite saying it was cross platform. It did use Java, so maybe it could be used but I did not like the first question it asked me so I dumped it.
I hope you remembered the name of the tool you liked. And maybe it was on this list:
http://en.wikipedia.org/wiki/Comparison_of_XML_editors
If others have any ideas after hearing me last night, I would be happy to hear it.