DiffMerge is a tool recently made freely available from SourceGear. If you are not a programmer then you probably have no need of this, but if you do find yourself needing to compare two different versions of source files, then I recommend this tool
I used WinMerge for a while, but the other day I needed to do the file comparison thing and I found that on my laptop, not only had I not installed WinMerge, I didn’t have an installer conveniently located in my c:\downloads folder either.
Since I regularly read Eric Sink’s Blog, I knew about DiffMerge, and so I gave it a try.
It’s excellent. It blows WinMerge out of the water. Recommended.
Editor’s Note, August 2020: Actually, I’ve ended up using both WinMerge and DIffMerge over the years. Perhaps WinMerge more. I would like to take back what I said here – they are both excellent tools and WinMerge perhaps has the edge but DiffMerge I still found handy for quick comparisons.