In this post, I’m going to tell you how to fill your computer with quality software that doesn’t cost anything. We’ll cover everything from the ground up – starting with the operating system, and then looking at web browsers, antivirus, email, office applications, and music, video, photo and instant messaging apps.

So let’s start with the question: “Why use free software?”. It’s a bit like that bit in an interview where you get asked ‘Why do you want this job?’. ‘Because I have rent to pay’ doesn’t normally cut it as an answer, but in this case it’s okay to be a cheapskate. Free software’s biggest benefit is simply that it doesn’t cost anything.

The benefits don’t stop there, though. Free software also means that you can try things out, tinker with different programs, without wasting cash. If you don’t like a bit of software, you don’t have to try to get a refund from whoever sold it to you – just uninstall.

Let’s start, then, at a very basic level – the operating system. You might be happy with Windows, or get Windows bundled with your PC, in which case you can sleep through the next minute or so. Right, those of you still awake – if you’re not happy with Microsoft’s world domination, though, then you might want to give Linux a try.

Linux has been around for a long time. It was originally based on Unix, which was released in 1970, but the GNU project – which Linux derives from – only kicked off in 1984. You might have heard that it’s difficult to use, or tricky, but there’s a version that exists that’s extremely user-friendly. It’s called Ubuntu.

Ubuntu, unlike Windows, releases new versions every six months or so. It’s built to be simple and fast, and is pre-loaded with free and open-source software. It won’t run everything that Windows might – it’s still a minority operating system – but it does have a component called WINE that can emulate Windows, so you can run programs that aren’t compatible (if a little slower) through that.

So, that’s the operating system sorted. What’s next? A web browser is almost always first on my list. The best bit of advice I could give to anyone with a computer is to ditch Internet Explorer and download either Firefox or Chrome to use instead. They both have their advantages and disadvantages, so let’s look at both.

I’ll start with Firefox, because it’s more widely used and known. Firefox is made by the Mozilla foundation, and will change the way you access the web thanks to its add-ons. These are little programs that complement your browser – doing everything from blocking adverts, to displaying a weather forecast or letting you take screenshots of websites. If you can imagine it, they’ll do it. It’s also faster and more secure than Microsoft’s Internet Explorer.

Chrome, on the other hand, is made by Google and sacrifices some of Firefox’s features for blazing speed. Chrome is wonderful because it just gets out of the way. The tabs are in the title bar, and the navigation icons are small, leaving maximum real estate for the actual page. It feels roomy, intuitive and just plan fast.

If you like features, add-ons and themes, then give Firefox a try. If you don’t care about any of that – you just want websites, and fast – then download Chrome. Both are considerably more secure than Internet Explorer, updated frequently, and – most importantly – absolutely free.

Even though you’re now more secure, there’s always the risk of viruses, so you better get a viruschecker. That aging copy of Norton that came installed on your PC but which ran out of its free trial a long time ago is like a leaky condom. It isn’t going to protect you one bit. But don’t worry – it’s easy to get free antivirus too.

Both Avast and AVG offer constantly updated virus protection absolutely free to the home user. Personally I use Avast, because I think Pirates are awesome, but there’s not a whole world of difference so just pick one and try it out. If you don’t like it, then uninstall and try the other. The companies offer the free version to home users as a marketing strategy – the idea being that they get their name out and businesses pay for the enterprise versions of the software.

Next up is email. Now, I know you’ve probably got Outlook set up with the email address supplied by your internet provider, but I want you to do me a favour – I want you to try out Google’s mail service – GMail. It’s absolutely excellent.

First of all, it will interface with just about any pre-existing email system, so there’s no need to change your email address – just set it up in GMail. Then you’ll notice the radically different interface, with messages grouped into conversations – not just discrete lumps of data – and tags replacing folders. It’s wonderful, and makes so much sense.

Then you’ll notice that you’re no longer getting any spam. Gmail’s spam filters are some of the best I’ve seen. I’ve had a GMail account for probably about five years now, and I could count on one hand the amount of times I’ve had spam creep into my inbox, or lose a real message to the spam folder. They’ve really got this one cracked.

Lastly, there’s the convenience of accessing it from anywhere. On any machine, you can just go to gmail dot com and view your emails. No hassle. Even if you’re away from your computer, there are gmail applications for every mobile device you can think of. No more excuses for not replying to that email. Sorry.

If you still really hate GMail then there’s an alternative. Thunderbird, which is the email-y cousin of Mozilla’s Firefox. It has the same extensions infrastructure as Firefox does, and it’s still light, fast and packed with features. Those who aren’t quite comfortable with web-based email should be quite happy with Thunderbird as an Outlook replacement.

That’s the essentials – an operating systems, a browser, antivirus and email checked off. We’ll have some fun with music and video in a minute, but first let’s look at free office suites, because we all have to work occasionally.

OpenOffice and Google Docs are the two choices that I’ll tell you about today. The former – OpenOffice – is downloadable software, but Google Docs is web-based.

OpenOffice pretty much does most of the stuff that Microsoft’s Office suite does – so if you’re used to that, then you’ll feel right at home. There’s an equivalent bit of software for Word, Excel, Access and Powerpoint, as well as a powerful drawing tool, too.

Each one isn’t quite as polished as the Microsoft eqivalent, but they’re all perfectly functional. They can read and save in Microsoft formats and will do pretty much anything that a normal user would need it to do. The package is completely free, and you can download it from openoffice dot org

Then there’s Google Docs. This, like GMail, is another ‘cloud’ service where you just use your web browser to do everything. It’s nowhere near as fully featured as OpenOffice – in fact it’s fairly simplistic, but it has the benefit of being accessible from anywhere. If you need to create something simple, or perhaps tweak a more complex document, then you should have no problems at all.

Right – onto the entertainment section. We don’t just use our PCs for work, right? We use them for music, video, photos, and chatting with family and friends. I like music, so let’s start with that.

Last.fm is a good place to start. The site carries that name because they want to be the last radio station you’ll ever need. It records what you listen to via plugins on your media player and then intelligently recommends you stuff that it thinks you might like based on that. You can then click ‘love’ or ‘ban’ on the recommendations and it’ll adjust accordingly.

Spotify is wonderful. I can’t say enough nice things about it. It looks a bit like iTunes, except that it’s got almost every song ever on it, and they stream in microseconds. Lastly, what about all those hundreds of MP3s that you acquired completely legally? You need something to play them too. I recommend Songbird.

Songbird is a bit like Firefox mashed up with iTunes. As well as managing your library and letting you make playlists and such, it also integrates a web browser. When you’re visiting any page with an MP3 – a music blog, for example – every linked MP3 shows up in a list at the bottom of the page for easy downloading. They then get automatically put into your library. Very useful, very well done. Completely open-source, and uses the same extensions infrastructure as Firefox.

So that’s music, how about video? There are two applications that I’ll recommend. The first is called VLC. It’s a media player that’ll play just about anything you throw at it. DivX, Xvid, MPG, support for pretty much everything is included – no mucking about with dodgy websites to get the codec you need. It’s not the most attractive application in the world, though, so those of you that aren’t keen, try might want to try out…

Media Player Classic – similar to VLC, but with a slightly nicer interface. Again, it’ll play most everything that you chuck at it, but I found VLC edges out in the reliability stakes. If you don’t like one, try the other.

As for content, it’s a little tougher to get good quality free video legally than it is for music, but the best out there, to be honest, is iPlayer. If you’ve not tried the BBC’s flash-based internet delivery system, then give it a shot. You’ll be pleasantly surprised. And in the UK it’s completely free.

Photos is next. I’m sure that following Dan’s talk about photography you’ve all got digital cameras spewing millions of pictures. You need to do two things – organize them and edit them. For organizational purposes, I’d suggest you check out Google’s Picasa. It lets you sort, tag, and organize all your millions of photos.

You can do basic editing tasks, like cropping and red-eye reduction, and you can make simple slideshows and collages from photos. Picasa makes it all very very easy. If you’re a bit more of a pro, and you need something a bit more hardcore, then take a look at GIMP.

GIMP is a fully open-sourced replacement for Photoshop. Note that I said replacement, not clone. Like Photoshop it’s ridiculously complex, but parts of the application work very differently, which will mean re-learning old habits if you’re a practiced Photoshop wizard.

If you’d like something in between – not as simplistic as just cropping and red-eye, but not as full-on as the GIMP, then I’d recommend Paint.net, which is a much much superior and easy-to-use version of Microsft Paint.

So, in terms of entertainment, music, video, and photos are covered. All that’s left is a way to talk to people – an instant messaging client.

The IM system that I’d recommend above all others is probably Skype. It lets you text-chat, voice-chat and video-chat to people across the world, and it’s got the best quality I’ve seen on such a service. I use it all the time, and when I was studying in America for a year with a girlfriend still in the UK, it probably saved our relationship.

But Skype is closed-source, and there are a lot of other communications networks out there too, so what you might want is something that ties in to everything else. Pidgin‘s for you. It supports MySpaceIM, MSN Messenger, Google Talk, Yahoo Messenger, Facebook Chat, Xfire and AIM, among others. Pretty much everything, basically.

That’s pretty much it. We’ve covered operating systems, web browsers, antivirus, email clients, office suites, music players and discovery services, video players, photos, and instant messaging. I think that’s most stuff that most people will need on a computer. And all of it is free.