XML I / O with Fitnesse

I want to create automated tests that accept XML and verify that the returned XML is what was expected. In addition, the end user should be able to add new data (XML input + expected XML output) without having to enter the code.

It seems that Fitnesse should do this, but I have not figured out how to do this yet.

Any recommendations? Tools other than Fitnesse that will work better? The code that needs testing is in .NET.

In the end, I would like to integrate these test results into a continuous integration server.

thank