If you are still buying software, you are wasting money.

Now that Mozilla's Firefox browser has achieved more than 20% market share in most parts of the world, people are slowly cottoning on to the benefits of free software.

Equally good is Mozilla's e-mail application, Thunderbird.

(For a, slightly complicated, and rather philosophical, explanation of free software, have a look here)

Less well known than Mozilla's internet applications, but a real money saver, is the free and fully-featured office suite, Open Office.  It is fully compatible with all major file formats and has just had an upgrade to version 3.0. Millions of people are now using it. You can download it here: http://www.openoffice.org/

According to this article in the Guardian on free and open source software, there are now 150 million people using Open Office:

http://www.guardian.co.uk/technology/2009/mar/12/open-source-apps

(Update, October 2011: After all sorts of corporate shenanigans over the last couple of years, many of the original developers of Open Office have set up a new project to improve on the Open Office software called Libre Office. Several IT press reviews have found Libre Office to be faster and more functional than Open Office.

http://www.libreoffice.org/

Most Linux distributions now include Libre Office rather than Open Office as their standard office suite.)

Here's quite a well-chosen list of the best free and open source software for Windows:

http://www.smashapps.org/2010/02/free-open-source-software-for-windows.html

PC Magazine also has an extensive list of the Best Free Software of 2010:

http://www.pcmag.com/article2/0,2817,2361876,00.asp

The website www.osalt.com is very good for finding free and open source alternatives to commercial software.

Why not switch to Linux?

However, rather than just downloading a few free applications to your existing virus-prone PC, why not install a new, reliable and secure operating system? Computers running Linux don't suffer from viruses. Both Debian and Ubuntu Linux have over 18,000 applications which allow you to do almost anything you could ever want with your computer for free.

I prefer Debian, both for its reliability and rock solid guarantees that it will always remain free. If you get to know Linux a bit better, you will find out that Ubuntu is in fact largely based on Debian.

Debian has definitely had less marketing glitz sprinkled on it than Ubuntu though, so if you are not very technical and/or would like to start using Linux on your own without any guidance, you might possibly be better off starting with Ubuntu. Even Ubuntu requires some learning, but presumably everyone who now uses a computer with a different operating system had to learn how to do so at some point. Most people still haven't learned how to combat viruses properly and that's something you don't have to worry about at all with Linux.

For a good up to date comparison of Ubuntu 9.10 and Windows 7 for normal users, have a look at this article in the Guardian:

http://www.guardian.co.uk/technology/2009/nov/04/windows-7-ubuntu-910-battle

Update January 2012: it would probably be worth pointing out that many people now consider Linux Mint to be the most user-friendly version of Linux. Personally I think Debian has now become just as easy to install and use as Ubuntu, as well as being faster and more reliable, particularly when upgrading to newer versions. Linux Mint may have the edge over Debian in terms of making it easy to install things like print drivers. Linux Mint has the advantage over Ubuntu that, like Debian, it is a completely free and independent project and not dependent on any one company with a particular commercial agenda. You can download Linux Mint here:

http://www.linuxmint.com/download.php

Installing Linux is now a lot simpler than you might think and there are very detailed instructions available, for example here. Essentially you download a copy of the installation disk and copy it onto a CD, then you put the CD into your computer's disk drive when you switch it on and follow the instructions.

If you need to buy a new computer, you can buy a computer from the UK supplier Novatech with no operating system for about £50 cheaper, allowing you to install your preferred version of Linux.

You'll be surprised at how simple and secure Linux is to use and if you have been used to paying through the nose for software you'll be truly astonished at the wealth of free applications available.

A lot cheaper than buying a new computer of course, is extending the life of an existing computer by installing Linux on it. A friend of mine has been using Debian Linux very successfully for the last couple of years on a nine year old machine that had been struggling with Windows 98.

Here's a picture of Debian Linux on my laptop (£290 from Novatech a couple of years ago). A lot more attractive in my opinion than some of the expensive alternatives:

If you're looking for advice on Linux you could get in touch with your local Linux user group, although there's more than enough information on the internet to get you going, as well as consumer magazines like Linux Format which you can find in all good newsagents (as they used to say):

http://www.linuxformat.co.uk/

All the Linux User Groups in the UK are listed here:

http://lug.org.uk/

Free online software

In addition to free software that you can install on your PC there is now also a wide range of free software that you can use on the web, such as Google docs which is especially good for sharing documents with friends and colleagues and Google Mail which provides a large amount of free e-mail storage space. Zoho also offers a wide range of free online applications: http://www.zoho.com/

FotoFlexer is a very good free, online photo editing application.

Dropbox is an enormously popular utility which provides online storage and download facilities - which makes it remarkably easy to transfer large files like photos rather than having to email them. The free version provides up to 2GB of storage space (which does pose some questions about their business model and how they propose to "monetise" their users.)

Whilst online services are no doubt handy for certain things, it's worth considering data privacy and security issues when using them. If, as some people are now starting to suggest, you were to store all your information online and for whatever reason it went missing, you'd have a bit of a problem. Most user agreements for online services give the service provider rights to trawl everything for targeted advertising purposes - a bit like inviting ITV to take a seat in your living room, which might or might not be a good thing...