Linux is an operating system, a large piece of software that manages a computer. It is similar to Microsoft Windows, but it is entirely free. The accurate name is GNU/Linux but "Linux" is used more often. The main reason to use it is that it is very secure, cannot have viruses, and fully available in Khmer now. The other reason is that nowadays it is graphically beautifull, easy to use and to maintain and you can work with other's people documents or hard drives without problems. You can even help your friends by rescuing their windows system when they fail because of a virus! (I do that all the time.)
Linux is not one company's product, but a number of companies and groups of people that contribute to it. In fact, the GNU/Linux system is a core component, which is branched off into many different products. They are called distributions.

When you put the Linux kernel together with useful software, an installer, and management utilities, you have a Linux distribution. Distributions change the appearance and function of Linux completely. They range from large, fully supported complete systems to lightweight ones that fit on a USB memory stick or run on old computers.

The first place to look for is the distributions websites and affiliated forums. Links in the list drives to a short description and documentation links hosted by DistroWatch.com. Alternatively you can write to the Phnom Penh Linux User Group, yes the PPLUG where we'll share our experience related to the distros we use everyday with pleasure. Or just ask me 012 561 005.

- If you are starting for home use, or for a Laptop, I reckon UBUNTU is probably the best,

- If you start a Desktop for home/small office, go for Fedora or Mandriva.

- With basic experience, you'll soon be able to install Debian, CentOS and suchlike.

If you want to try Linux but are not too sure, choose a LiveCD edition: these are a disk that you put in your drive, then reboot your computer. When it starts, it loads up only from RAM, without touching your hard drive so you can try without changing anything on your PC - it is a bit slow, but very good to see how it feels, and if everything is working.

Their inner workings may be different, but the true difference you'll see resides in their Window Manager (No, that is not how they manage your micro$oft software - they don't!). The Window Manager (WM) is the graphic interface that is used to interact with your computer; Gnome (UBUNTU, Fedora) is completely different from anything else, and really easy to learn; KDE may look more familiar but is actually filled with so much tweaks and subtleties that it'd probably take you months just to get a comprehensive picture. More exotic options includes the lightweight XFCE4, both elegant, tweak-able and less resources-hungry, and some other, usually faster, with either strong visual impact (Enlightenment) or very small footprint (Blackbox) but a steeper learning curve.

I use the very stable Slackware 12.2 on a Core2Duo 2.66 with 2G's of ram and an array of RAID disks for Data Safety; My Window Manager of choice is Enlightenment DR16 which takes 2.5 seconds to boot (that is to compare to 20/30 with Gnome/KDE) Lots of screens here. On that system, I use the KDE software stack like Konqueror for file management or KDEPIM mail/calendar/address book suite. Right now, my desktop while working on this looks like THIS where you'll see my separate hard drives with the current .iso files on each side, a view on the webpage in the center and two little windows to drag'n'drop between my computer and the webserver connected through FTP. That is the power of Linux, all in a single konqueror instance!

You should actually ask your question the other way around: 'I have this hardware, what Linux can I run on it?". Depending on the age of your machine, its processor and graphic abilities there is a wide range of choice of Linux that can run on; from 50 Mb mini-distros like DSL to full-featured, multimedia champions with cool graphics like Linux Mint. In between all that, you should define what will be your use of the machine; as such, as of now, I never met a cdrom-equipped desktop that wasn't good enough to run a small distro with all that you need for office work or to host a webserver; people may always drool over super-power machines, but the fact is that you don't really need that much of power to run Linux - see all the NetBooks out there, the EeePC, AspireOne and the like: they run slow, on 512megs of memory, on single core cpus... Save the Planet: Use Linux!