I wrote this article as a guide for people on how to start with using Open Source and Free softwares.
The guide is organized into steps and hints about choices and ways to implement each choice.
Keep in mind that the applications or tutorials i mention here are not
ones i promote as the best available, as there might be better ones
that you can find by doing some research on the net by using keywords
from this article for example, also ones that suit certain scenarios or
use case requirements more than the others.
At first you will be faced with having to decide about if you are going
to keep using a none Linux | BSD distribution like Microsoft Windows,
or completely migrate to a Linux | BSD distribution.
The choices you have are:
1- Use Free and Open Source softwares available while running Microsoft Windows
2- Same as point (1) and in addition run a Linux | BSD distribution in a virtual machine
3- Reverse of point (2) running a Linux | BSD distribution as a host and Microsoft Windows as a guest in a virtual machine

4- Using Dual Boot between Microsoft Windows and a Linux | BSD distribution
5- Running a Linux | BSD distribution alone
Lets pass again by each point with more details now, but from now on
i will replace "Open Source Software" with "OSS" every time i want to
mention Open Source Software, and OSS will be globally referring to
both Free and Open Source Software. PS will refer to Proprietary
Software.
1- The safe start:
There are lots of softwares that are OSS and run under Microsoft
Windows, a website that i know where they have a directory of OSS as
alternatives to PS is osalt.com.
But still i will list below the most commonly used ones for daily usage:
- Internet Browser: FireFox

- Instant Messenger: Pidgin
- Email Client: Thunderbird
- Office Suite: OpenOffice
- Calendaring and Tasks: Lightning & Sunbird
- VOIP Softphone: QuteCom

- FTP & File Sharing client: FileZilla
- Image & Photo Editing: Gimp
- 2D Vector Graphics: Inkscape
- 3D Animation and Modeling: Blender
- Music Player: SongBird

- Movie Player: MPlayer
Yes this is the "Safe Start", but there is the "Lazy & Safe Start", which is getting PortableApps where you have most if not all the applications i mentioned above available.
2- You are Familiar with virtualization and you want to test Linux
You can install VirtualBox and create a Linux machine.

Here you will find a list of Linux distributions and a comparison matrix between them.
But i recommend you get Ubuntu , as it is known to be the most user friendly linux flavor and that works well out of the box.
3- Facts is you will still need Windows sometimes for compatibility issues
After you decide that you want to install Ubuntu as main OS , you can find help online at the Ubuntu website, or you can join the #ubuntu-lb irc support channel on irc.freenode.net server (or visit http://ubuntu-lb.com/chat ) and ask for help with installing and using Ubuntu.

It is recommended as well to consult this page Hardware Support to make sure your hardware is supported by Ubuntu.
And if you find yourself sometimes you need to boot a Windows machine,
you can install VirtualBox and create a Windows machine and install
Windows on it. But i will have to warn you that the one that comes
installed on your hardware might not run well because it will detect
that it is running on a machine it is not pre-compiled for it.
If you are going to buy a new system tell the retailer that you don't
want Windows on it and ask them to reduce the price of Windows from the
overall price, and buy a standalone Windows DVD.
4- You have space on your system enough to have two operating systems co-exist
You are not satisfied with the performance while running Linux or
Windows in a virtual machine, you decide that you want to use dual
boot. The disadvantage of this method is you will not be able to run
both operating systems at the same time.
You can refer to this Dual Boot Tutorial or join the #ubuntu-lb channel for help with running in dual boot model.

5- Linux Server or Spare Machine
You want to have a system dedicated to running Linux either because
you don't need more than that, or you plan to run a server (e.g Web
Server, Mail Server, DNS Server, etc...).
A way to start with running a server is by getting Ubuntu Server Edition, or get another Linux or BSD distribution that is more suitable depending on your needs.
For a list of BSD variants go to : BSD variants .
At Last
After you are done with installing a Linux | BSD distribution, it is
time to install software packages, in order to do this you can use the
software package manager available for the distribution you are using.

For example in case your choice was Ubuntu refer to Adding, Removing and Updating Applications on Ubuntu website.
For a detailed tutorial on how to migrate to Ubuntu visit the page Switching From Windows .
And finally if you want to build your own Linux distribution go to Linux From Scratch
You don't trust you can do it by your own? let us know by submitting the Install Fest Petition Form
Good luck , have fun and enjoy your freedom!