Being a really keen supporter of all things open source here are a few programmes that are open source that might be of use to you. For more information on the Open Source Initiative (OSI), what Open Source means, and for a more definitive list of software out there try http://www.opensource.org
Here's a list of some fab OS software programmes...
Web Browsing - Mozilla Firefox
The premier free, open-source browser. Tabs, pop-up blocking, themes, and extensions. Considered by many to be the world's best browser.
Sound Editor and Recorder – Audacity
This free, open-source, user friendly and small application will let you record and edit audio easily. You can also download a wrapper for VST plug-ins.
FTP - SFTP Client - Filezilla
Very useful free, open-source, FTP and SFTP Client. “I would suggest this to access my Client Server with.” It makes uploading and downloading files a lot quicker than a computer's browser.
File and Archive Manager – PeaZip
With a full and portable version PeaZip zips and unzips pretty much every type of compressed file, without any ‘trial version problems’. “This is my favourite programme of the moment.”
Video File Format Converter – Handbreak
Convert from and too a massive amount of formats. Nice easy to use selection buttons and include default settings for YouTube and mobile device formats.