I let this blog slide a long time since when I moved house and couldn't spare the time for it.
But sometimes you learn something that's just so astounding, you have to share it with the world.
Word can diff the current document against another one. It's an option under Track Changes. I'm on Word 2000 so it's clearly been there for ever even though I've constantly moaned about the lack of such a feature.
Gosh.