CompareIt! is really a great tool. Get the Vers4 Beta, it is very stable and has many more features, like binary editing etc.
The developer is also extremely responsive: I have asked for features and sometimes within a day or two they were added to the program.
The program is very lightweight on resources and easy to use. Does image comparison too. There is a unicode version. For some reason I remember the DC discount to be 60% not 50%, though I bought it before the DC discount appeared.
If you buy the bundle with SynchronizeIt! (and again use the 3.4beta here), which IMHO is the best all around synchronizing app, you save a lot with the bundling price on top.