Serofth: As bert_the_turtle implicitly stated, the .dat files are, in fact, archived files. .rar is a little like .zip---a bunch of files are put into an archive and compressed, making it easier to send them from one place to another, and making them a bit smaller. The last time I checked, Mac OS X does not natively handle .rar archives (though I am still running 10.5, so 10.6 may have changed things around a bit). So you will probably need to download a utility to help you out, such as
UnRarX. Once you have downloaded UnRarX, you should be able to simply drag the .dat file to the UnRarX application, and it will automatically unpack it, creating a data/ directory in the Defcon application bundle, in the same place as the .dat files.
xander