Re: what is RPM's and tar.gz
GNU/Linux is not as straightforward as Windows. In Windows, formats are rather limited such as .doc for documents and .exe for installers. In GNU/Linux, there can be numerous formats. It takes a little getting used to but most of the time you'll be sticking to the same few formats such as .sxw for documents, .ogg for media files and RPMs for installing software.
Install GNU/Linux and be Free!