Why Linux, and why Debian / Fedora / Ubuntu?
Linux is a free operating system. An operating system is the most important piece of software on your computer because it allows other programs to run on top of it - other examples include Windows, MacOS and UNIX. I'm sure you know all this but if not, check out the wikipedia entry.
Why should anyone use Linux as their main OS? Why not use Windows or MacOS? The usual answer given to this question is freedom. Not just because you can download Linux and programs that run on it for free, but because the communities that create open source software want to create open software that anyone can distribute, modify and use.
Some people refer to Linux as GNU/Linux. The gnu.org website explains free software at length.
So why do I love the geeky world of Linux? Well, I've been using computers for a very long time now, and I'm pretty sure it all started with the Commodore C16 plus 4 my sister gave me when she got bored of it. We still reminisce about games like "Fire Ant" and "Icicle Works" from time to time. After that I was bought a Commodore C64 and started programming in BASIC. I think I was doomed from that point on.
Of course, eventually the beginnings of the modern home PC came along and I became the proud owner of an IBM PS2/E (never sure if that one was a 386 or a 486... I spent much of my time trying to make DOS games run with memmaker.
Later on came the Pentium class machines. Thus began my long standing relationship with the Microsoft Windows operating system. My work with computers providing support has involved networks using every Windows OS from 3.11 to Windows 7 (and Server 2008).
All very interesting but why does Linux come into this then? Well, we can safely safe that I'm a proper computer nerd, and happy to be so. It pays my rent. So in my job, I work with the Windows OS all day.
I'd tried Linux a few times before but like many I just couldn't wrap my head 'round it. A couple of years ago though, I decided to give it another try. I got into Fedora and Ubuntu, did some distro hopping (see below!) and eventually settled on Fedora because it's sufficiently geeky to keep me happy but usable enough so I don't get in a foul mood every five minutes. Simply put, it's a new challenge, and it pushes me further and forces me to keep learning. Also, the Linux operating system has a way of growing on you, even with the minor frustrations it can throw at you at times. Seriously, it's elegantly designed. Trust me on this, if you've ever spent hours removing cack from a Windows registry, you'll appreciate the fact that Linux uses simple text files for configuration. Sounds basic? Not on your life! ;)
Unlike some Linux users out there, I don't think Microsoft are evil. Well, not ALL the time anyway. They're a business - a highly successful business that have successfully put together an operating system that most people can use. That's quite an achievement. Thing is though, Microsoft insist on doing bizarre things sometimes. Take the Office 2007 ribbon interface. Why? Why would any sane developer remove the interface office staff all over the world have learnt to use and replace it with a completely different one WITH NO OPTION TO CHANGE IT BACK?! ...and while we're on the subject I'm sick of people saying how great Windows 7 is. It's Vista but it isn't bloated and they took out UAC. All of a sudden we're applauding them for releasing an unbroken version of the Vista operating system they released 3 YEARS AGO... ...Ahem. Rant over, I promise.
Moving on... rapidly. If you like Windows, good for you - as long as it does what you need it to. Linux is a beautifully made operating system, but you have to think back and remember how long it took you to learn Windows / Mac / whatever the first time around.
People are unlikely to move over to Linux if their current system addresses their needs, because they would have to invest a lot of time relearning a lot of the basics. For me, learning new skills is part of why I love I.T., but for a lot of people, they need to feel comfortable in what they already know so they can be productive.
Why should you use Debian? Debian is a distribution ('distro') of Linux. As most of the software for Linux is free, individuals, companies or communities can put together their own version of Linux, with whatever software they want. This helps to tailor a distribution to a particular niche. I've toyed with various distributions, Fedora and Ubuntu mostly (moving from one distro to another is called 'distro hopping'). I didn't switch to Debian until I had to try and find an operating system that would work on a ten-year old laptop. Out of all the distributions I tried, Debian was the most suited.
Debian is perfectly suited to someone who has gotten used to Ubuntu, and wants to configure their system their own way. The key point is that Debian by default is a very stable OS, but with a little tinkering, you can install the most up-to-date, bleeding edge version of an application that may not be as thoroughly tested.
Debian excels in a server role because of its stability.
Why should you use Fedora? Fedora 12 has just been released and (like Fedora 11 before it) it's an excellent distro. I've been so impressed it has now replaced Debian on most of my computers (except the ten year old laptop). It seems to combine some of the elements of Ubuntu (in terms of ease of use), while still being suited to the more experienced user. It takes a little setting up, but if you know what you're doing, that can a good thing... )
Fedora is one of the most "cutting edge" distros in that it has a rolling six month release cycle, and in many ways forms the basis of Red Hat's commercial product (Red Hat Enterprise Linux). Again, Fedora does well in a server role, but for a production server, you may want to consider Debian or CentOS (which uses the open source Red Hat Enterprise Linux packages which are more stable). CentOS is still free unlike the commercial Red Hat products, but you pretty much have to provide your own support.
I'd still recommend Ubuntu as a good distribution for beginners, as the focus is on trying to make the system as well integrated and as easy to use as possible. It's generally stable as it's based on Debian. Ubuntu also has a 6 month upgrade cycle, just like Fedora.
Ubuntu excels because it tries to make the Linux desktop easier for first time users to use. The philosphy is very much "everything should just work". This has been fantastic for Linux in general because it forces the OS out of the realm of the pure geek, and into the public domain where non-experts can benefit from a free OS. Also, it makes all the other distros play catch up, because Ubuntu releases are usually excellent.
There are many other distributions, such as OpenSUSE, Mandriva, Slackware, Gentoo, etc. There are also other free UNIX based operating systems such as FreeBSD, OpenBSD and OpenSolaris. Usually all of these distributions have been created to fill a particular niche.
One of the reasons I've been impressed by Fedora lately is the sheer number of improvements that they seem to be adding. They really get behind the technology, which I suppose Novell (OpenSUSE) do as well. Ubuntu tends to be more about how everything works, not pushing the technology forward. It's good when distributions create new software - for example, TigerVNC is a distinct improvement over TightVNC.
I guess the only answer that makes sense is that if you like Windows, then use Windows. If you like Ubuntu, that's great too. There's nothing wrong with using something popular - after all, there's more chance of getting help if you run into problems. But where's the challenge in that, eh? ;)