I think that the best way to do it will be like most of the program do - split the view windows to two and show old and new version and the changed text marked.
SVN, Word and many other programs I know does it the same way. I know that some programs that can't show compare at least open the correct program, for example when I try to compare two Word documents in SVN it opens Word on my PC with these two documents in compare more. I sow this post that may help:
Code: Select allI simply use the TortoiseSVN diff scripts for this purpose. These are just .js-files, which support some formats (doc/docx, for instance) and open them, turning the application (MS Word) into compare mode. The syntax is pretty clear:
>diff-doc.js file1.doc file2.doc
About the documents type - the more the better, most important is Office documents I think.