System
Here are all the programs you need for basic things.
Distribution
Well, you may have already chosen your distribution, but I really suggest you try Debian as soon as possible. Debian is a unique Linux distribution since it is made by the users themselves - just as Linux. Thus, it is also for free: You can download it or buy it as CD-ROM from their mail-order but these do cost some bucks. Debian is available in three versions: "stable", "testing" and "unstable". The names already describe the differences: In "stable", there are only the programs that have been tested for some time and therefore are stable; thus "stable" is widly used for servers that should run all the time and new program versions are not that important. The opposite is "unstable" in which are the very recent programs that may be (very) unstable, so it should only be used by developers. In "testing" are programs that have been in "unstable" for some days and have not caused problems. So, I recommend "testing" for desktop users if the versions from "stable" are too old.
A big advantage of Debian is the package-management that is done with a database that includes the packages and its dependencies. At the moment there are about 19.000 packages in the database. One can update and install new packages very easily. It is also possible to transfer the selection of the installed packages form one computer to another and let the second install the packages automatically.
Desktop Environment
The two popular desktop environments KDE and GNOME have became very functional but also big and slow. XFCE is a desktop environment that has been made to be lean, fast and supportive of freedesktop standards, that are also supported by KDE and GNOME. So, XFCE supports a system tray that can be used by programs to show its status and XFCE has got a compositioning manager that accelrates transparency of windows.
XFCE [de|en]
Freedesktop [en]
X.org [en]
GNOME [en]
KDE [en]
Cryptographic Filesystem
In order to make the data (e.g. your GnuPG secret! key) on your harddisk unavailable for other people, use CFS. You mount it with a passphrase and then every program has access until you unmount it.
Printing System
With CUPS the use of printers becomes very easy. You just open http://localhost:631 with a browser and can then install and configure the printer and the queue. If CUPS is acting as a print-server, you can do this on each client after you have entered a special password. CUPS is compatible with the lpr command.
RAM Test
Memtest86 vets your RAM. It does not run under Linux, but can installed under Linux and can be loaded by e.g. lilo. Thus, it does not depend on any operating system.
