Switching to a free and open source operating system has never been easier. A plethora of tools and applications are already cross-platform and there are many free software alternatives to common applications you may already use.
If you work with Microsoft Office
Many free and open source operating systems have the LibreOffice suite available which lets you create documents, spreadsheets, and presentations as you would with Microsoft Office. With LibreOffice, you can also open and edit any Word, Powerpoint, or Excel files you may already have.
Browsing the Web
You still have the best of the web available to you on free and open source operating systems. Popular browsers like Google Chrome, Mozilla Firefox and Opera all provide versions that support Linux, just to name a few.
Open your Creativity
On other platforms, the creative field is dominated by proprietary applications, but there are several capable free and open source alternatives. Together the GIMP, Inkscape and Krita make a great set of tools for graphic editing and illustration. If animation or modelling is your thing, Blender is a great open source tool for 3D graphics. The Ardour digital audio workstation and Audacity multi-track editor is out there for you audiophiles. Plus Scribus exists for desktop publishing.
Keep on Listening
Out of the box, many free and open source operating systems can manage your existing music library and keep you listening. But if music streaming is your thing, Spotify is one of the few services to support Linux.
Gaming on Linux has never been more possible. The number of Linux-compatible games available is rapidly growing on platforms like Steam and GOG.com and there is growing support, especially among indie developers, for Linux as a platform.