Line by line diff (file comparison) with HTML/RTF export

Hello everyone

Can anyone recommend a program that can compare two text files, line by line, and output the difference (preferably character differences) to a format that can be opened in MS Word, e.g. DOC, RTF or HTML? I need a tool that will compare each line from file 1 with the same line from file 2. The differences should be highlighted or should be displayed as strike-through/underline.

I have WinMerge on my computer, but WinMerge is trying to be clever and assumes that lines were deleted in the files, so at some point it no longer compares line n in the one file with line n in the other file.

There are some online tools that actually work quite well, but I can only view the results on line (can't save it).

I know I can do "compare documents" in MS Word, but even MS Word sometimes tries to be clever and starts comparing the wrong lines with each other if it hits a patch of seemingly large differences in the middle of the file. I know that if I use "compare documents" in MS Word after converting the text to a table, the accuracy improves, but it still does that be-too-clever thing.

Thanks
Samuel

PS. 99% of the lines in my files have differences, ranging from one character all the way to the entire line.