Software I've found handy
Firefox free web browser.
Thunderbird free email client.
AutoIT tiny GUI automation tool
Perl programming language
PHP programming language
Java programming language
Azureus open source Bit Torrent client.
OpenOffice open source
OpenWorkbench project management tool
Copernic desktop search tool
KDE desktop environment
Audacity open source software for recording and editing sounds.
For more info on free or open source software, look here:
Beginner's note: essentially, you can think of "open source" as "free".