Note, these apps are free — not all of them are open source.

  • OpenOffice – not quite as advanced as Microsoft Office and doesn’t have SharePoint integration, but if that doesn’t matter then look no further (check out Novell’s version too)
  • Mozilla Firefox – just as secure as IE7 but insanely customisable. The best browsing experience available
  • Mozilla Thunderbird – outstanding customisable email (make sure you install Lightning as well)
  • Evolution – yes, it’s been ported to Windows, and is an excellent corporate groupware product
  • Mozilla SunBird – if you prefer a separate application for calendaring, this is the one for you
  • Pidgin – chat on every network through one lightweight open-source program, with none of the banner ads and hoop-jumping the official clients put you through.
  • Media Player Classic – lightweight media player with lots of useful addins (like DVD playback)
  • The GIMP – still one of the best image editing packages out there
  • K-Lite Mega Codec Pack – play any media file available (includes Media Player Classic)
  • VLC Media Player – cross-platform media player and streaming server
  • MediaCoder – can convert pretty much anything to anything and back again
  • Winamp – still the best music player, in my opinion
  • RSSOwl – if you prefer a separate app to manage newsfeed/RSS/XML/Atom subscriptions, this is the one
  • Juice – any podcast, any format
  • AVG Anti-Virus – still kicking goals. Lightweight, stable and offers great realtime protection
  • AVG Anti-Spyware – manual updates required for the free version, but still very good
  • Ad-Aware Free – despite the push towards licensing, the free version is still great
  • Spybot – still free, still powerful
  • Azureus – a powerful and very advanced Java-based torrent client
  • PrimoPDF – convert pretty much anything to PDF

Source APC Magazine