For novices, Ubuntu is a good start - there are a lot of tools available which make the pernickety stuff like installing codecs a breeze. Indeed, the stated goal of Ubuntu is to deliver a free, open source operating system focused on usability.

It comes in three main flavours which suit different tastes and different computer specs - Ubuntu, which uses the GNOME desktop environment; Kubuntu, which uses KDE; and Xubuntu, which uses XFCE. XFCE is well-suited to lower end machines, whereas K/Ubuntu are better suited to mid-range and up. Install a proprietary driver for your nVidia/ATi graphics card, switch on composited desktop effects, and get some eye-candy that outclasses both Vista and Leopard (IMO).

Aside from that, there is Fluxbuntu, which uses Fluxbox as its desktop environment. It's so lightweight that it will make your computer fly. There's also Open GEU, and many other derivatives that suit individual needs and systems.

You might have guessed that I'm a bit of an Ubuntu fan. That said, I still use Windows XP for a lot of stuff - I love games, particularly Battlefield 2, which doesn't run natively on Linux, and requires WINE to run. Basically, WINE allows Linux users to run Windows software without having to boot into Windows. It's problematic, however, in that the list of compatible software is limited, and even those programs that do work under WINE don't always work perfectly. Furthermore, printer, scanner and webcam support is still poor - my printer is a Brother DCP-135C. Brother have released an open-source driver for the printer functions, but it's buggy and there is currently no support for the scanner under Ubuntu Gutsy (the latest version). My webcam used to cause the OS to lock up if I turned it on until the release of Gutsy, and even though it works now, there is no way to effectively manage the camera exposure, contrast, and brightness - if I want to use Skype at night, I have to turn the light on! :/

Nevertheless, Linux makes a good home media centre, with LinuxMCE doing some good work. incidentally, it's based on Ubuntu, although you can install software like MythTV on practically any Linux distribution. Of course, it's dependent on your hardware being capable of decoding the media.

I also like the Fedora Project - it has a much more 'solid' feel to it than Ubuntu. I guess this derives from the fact that it functions as an upstream, quasi-beta version of Red Hat Enterprise Linux. That doesn't mean it's unstable, though - I've never had Fedora 8 or Ubuntu 7.10 crash on me, and I've only made earlier versions crash through my webcam. Stability is a key quality of Linux. I've been told many times that it's less 'useful' than Windows (often by people that have very particular uses for their OS), or that Linux is 'only useful on servers', but I do feel that for general purposes (excluding gaming and writing music -one of my hobbies) that it's actually excellent and in some ways better suited for my purposes than Windows.