Found a pretty neat XML editor at http://www.exchangerxml.com/index.html but it is very confusing, it claims that there is a free version and a commercial version but I was unable to find the commercial version. All the features indicated on the commercial is found in the version I downloaded but did not see a way to register. This is a good editor since it also provides for XSLT editing.
Alternative ones without XSLT debugging capabilities are found in the following:
Personally I still like XSLTMajic from Microsoft that was discontinued support severals years ago. Managed to find the link.