The 'GZ' or 'BZ2' section refers to the fact the compression method is gzip or bzip2. TAR.GZ and TAR.BZ2 files are compressed archives originating from GNU/Linux. The 7-Zip program includes support for RAR 3.0, but the RAR component is proprietary.
If RAR 3.0 is needed, taking a newer CVS snapshot may work, which has been done for the unrar-free Debian and Ubuntu packages. The free software (as in freedom) unrar can unpack RAR files that do not use RAR 3.0 or later. WinRAR is the original tool for RAR, available for many platforms, WinRAR has a trial period BUT the trial period never ends so you can have the software forever for free. RAR files are compressed using a proprietary format. Most (if not all) GNU/Linux distributions include Info-ZIP, which can be used to decompress ZIP files, along with a GUI frontend, such as File Roller for GNOME and Ark for KDE. ZIP files can be extracted easily in Windows and GNU/Linux with the utilities included with your OS.
