Software

Here is a list of useful software, all of which is open-source and completely free.

Firefox - The best web browser. It is a cross-platform browser, providing support for various versions of Microsoft Windows, Mac OS X, and Linux. Features included with Firefox are tabbed browsing, incremental find (via the Find toolbar), Live bookmarking, an integrated download manager, and a search system.
Thunderbird - email & news reader.
Pidgin - instant messenger - talk to your friends using AIM, ICQ, Jabber/XMPP, MSN Messenger, Yahoo!, Bonjour, Gadu-Gadu, IRC, Novell GroupWise Messenger, QQ, Lotus Sametime, SILC, SIMPLE, and Zephyr.
Skype - make telephone calls from their computer to other Skype users free of charge.
Openoffice - A multi-platform and multi-lingual full office suite.
The Gimp - the GNU Image mainpulation program- for retouching photos and general artistic designs..
Blender - 3d modelling, animation & rendering.
Scribus - Desk top publishing.
Inkscape - Vector graphics editor.