KDiff3, better then WinDiff!

KDiff3 - Homepage: "KDiff3 is a program that

* compares or merges two or three text input files or directories,
* shows the differences line by line and character by character (!),
* provides an automatic merge-facility and
* an integrated editor for comfortable solving of merge-conflicts,
* supports Unicode, UTF-8 and other codecs,
* supports KIO on KDE (allows accessing ftp, sftp, fish, smb etc.),
* and has an intuitive graphical user interface.
* Read what else is special in a short"

Windiff: For file/folder comparison under windows.

To compare files and display the results graphically, use Windiff.exe.
windiff.zip
Command line usage