For the past several years I have been using Open Source Software (OSS). In simple terms, that means computer programs whose source code is publicly available so that others can modify it if desired. Microsoft is NOT open source; their code is proprietary and is not published, so you can't alter it (not legally anyway).

Most open source software is free of charge, but some of it requires purchasing. That's often the case with specialist software that has a support contract included. Many of the people who write OSS do so in their own time without being paid for it, whilst others are employed to write OSS.

You may already be using open source software without realising it. For example, the Mozilla Firefox web browser and the Mozilla Thunderbird email client are OSS – not surprising since the Mozilla Foundation is devoted to supporting open source software projects such as Firefox and Thunderbird amongst others.

Mozilla make software for multiple platforms, eg people using Windows, Apple Mac and Linux operating systems can all have a version of Firefox or Thunderbird for their operating system.

Trying to be 100% OSS means giving up Microsoft altogether. I've done that. I use the Ubuntu Linux operating system instead of Windows, and I am extremely happy to have made that switch. Its true that there are a few software manufacturers who do not provide a Linux version of software – in particular, genealogy programs for Linux are very thin on the ground. There are ways around that. You can run an instance of Windows in a “virtual machine” - that's a program inside Linux that lets a licensed copy of Windows run inside Linux; or you can install a program like Wine that allows some Windows software to run in Linux directly.

There are (too) many different “flavours” of Linux, produced by different people or companies. These are generally referred to as distributions, or “distros” for short. The advantages of using Linux are:

• Almost all distributions are free of charge. There's none of that annoying “activation” nonsense required for home users of Windows.

• Computer scams, virus writers and other criminal activity almost all target users of the Windows operating system, so Linux is relatively unlikely to be affected by these risks (though I still have antivirus installed just in case). Plus many "system" functions in Linux can only be run by the 'root' user which requires a password to be entered, unlike Windows where any user (including a virus/worm/trojan) can execute system changes.
  

• Linux tends to boot faster and programs generally run faster.

• Programs don't tend to “freeze” often, unlike in Windows. If they do, the task manager allows you to “kill” the program almost instantly, whereas Windows tends to take a long time even to do that.

• There are thousands of excellent software programs available to Linux users, almost all of them free of charge. That includes OpenOffice, a complete office suite replacement for Microsoft Office (and its free).

• When you install Linux on a machine it just works. Unlike Windows, you don't need to also install mainboard drivers, network drivers, sound drivers, display drivers, modem drivers, etc ad nauseam. Remember that next time you have to re-build a Windows PC.

• Ultimately, my main reason for using OSS is that I feel its immoral for governments to spend millions of taxpayer dollars in software licensing fees (which go to the USA) when they could get equivalent software free of charge and spend that money right at home on training users and employing suitably skilled support staff. That's better for our local economy and it allows people to customise software solutions for their enterprise, instead of being locked into one company's solution (Microsoft's or anyone else's).

Yes it is true that some hardware vendors have not released Linux drivers for inclusion in distros, but that situation is rapidly improving. Then again, plenty of hardware (especially printers) won't work in Windows Vista either, because Microsoft choose to make it that way. Personally I have had very little trouble using Linux; my digital camera, webcam, printers, USB drives, bluetooth dongle, etc all work in Ubuntu straight out of the box.

One disappointment I have had with OSS is that the otherwise-excellent OpenOffice program (which I use daily) has a really frustrating and sometimes near-unusable mail merge feature. And it doesn't really handle merging labels (which is way the most common merge that I need). Fortunately there is a nice easy workaround for this which many OOO users may not know, and I'm putting it here for all to see as it took a lot of searching on the web to find this solution. Note: this works on OOO version 2 but I've not yet tested on OOO v3

For document merges see Steph's solution which is no longer online but I have saved it as a 700kb PDF file here
This is a much better mail-merge solution for Open Office than any I have seen.

and for label merges, see my adaptation of the above technique here (about 400kb PDF).

Doing mail-merges (incl email merges) and label merges is now a doddle using the above methods.