In Linux the shell (or terminal) is the lifeline of the developer, and of any power user. Things which can be done on the GUI (by clicking on different buttons), can be done much more efficiently on the terminal by using commands. Maybe one can not remember all the commands, but with regular usage one can easily remember the most useful ones. The following guide will introduce you to a minimal set of basic commands required to use your Linux computer efficiently.
Linux is available (also via internet) in different distributions (S.u.S.E., Fedora, Debian etc.). Meanwhile there is a variety of direct-start (live) systems, which can be started, without installation, directly from CD or other bootable storage devices (Knoppix, Ubuntu, . . . ). There are also interesting “mini versions” ( <100 MB) designed for a start from USBsticks (e.g., Puppy). The source code of Linux is free.