Highlighting changes in a diff report

Hi there,

I am looking for ways to create a HTML report of a comparison between two
versions of a XML file, so basically I would need to create a function that
compares the original file with the edited version. I would like to display
the differences with some formatting as in a word processor's track
changing mode.

For example (simplified case), given the two XML files, i.e. Orig.xml:

<doc>
<string>This is a string</string>
</doc>

and Edited.xml:

<doc ver="new">
<string>This is a text</string>
</doc>

I would like the output report to show something like this:

...
<td>This is a <span style="color: red;"><del>string</del></span><span
style="color: blue;"><ins>text</ins></span></td>
...

Before I start getting my head around this, I wanted to have an expert's
opinion: Can this be done easily with XSLT? (for a basic-level programmer
like me, that is)

I know formatting the output in HTML is not a problem, but finding the
exact differences between the two files might be. Only text content of some
elements (and always the same kind of element) should vary, not the
structure of the document.

My first preference would be to create a stylesheet because I can integrate
it in my workflows, but if this is difficult a ready-made tool would be
good as well as long as it's not too expensive (DeltaXML is too expensive).

I hope someone can advise and even point me in the right direction. Thank
you very much in advance.

Cheers,
Manuel