Interesting tool: [1] http://winmerge.org/

To quote the authors: WinMerge is an Open Source visual text file differencing and merging tool for Win32 platforms. It is highly useful for determing what has changed between project versions, and then merging changes between versions.

I have previously used to use windiff.exe to diff two files. This is or was part of the Windows Resource Kit. More recently I have used the freeware Context editor [2] http://context.cx, which has a very good diff tool built in.

On a related note, Here’s a cool trick for finding registry differences between two machines: Export the subkey to a file for each machine and use a file diff tool to compare the differences. By default, the registry editor exports unicode, so either your diff tool has to support unicode, or you need to use the optional Win NT4/9x output format for your export.