Who is this thread for?
This thread is for people new to linux who are confused by all the choices available, specifically the window managers (from hereon "WM"). If you keep hearing words like Gnome, KDE, XFCE4, enlightenment, Fluxbox and IceWM and are confused as to what it all means, then this thread is for you.

What is this thread about?
This thread is here to try to break down the most basic info about the most popular WM available. It it is here to list some quick advantages and disadvantages of each, as well as recommended uses and most noteworthy differences. All in all, after reading this a novice should be able to at least have a slight idea of what WM does what and which one may best suit his or her computing needs.

What is a WM and how do I use it?
Leaving out the complicated computer terms, a WM is an essential part of any GUI interface. Of course if you miss your old DOS days and the only reason you switched to Linux is so that you can use command line in 10 virtual prompts you won't need to know any of this. However, if you are like the rest of us and like to use your mouse for point-and-click action, then you will need a WM. Windows gives you one choice: Explorer. Linux gives you many choices. A WM basically enables you to have multiple applications open in a single window for multi-tasking. It also provides you with a file browser, and other important tid-bits like a clock, and convenient menus so you don't have to find all your applications in the /usr/bin and /usr/sbin folders.

That said, lets get started on the meat of this stuff:

KDE - K Desktop Environment - Conquer your Desktop!
http://www.kde.org

KDE is the most Windows-esque WM available for Linux, though it is not by any means an Explorer clone. By many estimates this is the most popular WM. It is based heavily around the QT toolkit. What this means to you is for sake of fewer dependencies and better appearance you should strive to use QT-based applications as much as possible, rather than GTK apps. Luckily that shouldn't be too difficult since there are plenty available. Konqueror is where it all happens however. It is KDE's file browser and Web browser (using KHTML engine, which Apple also uses for Safari). KDE is known to be big and it likes to have RAM and CPU resources, so it is not recommended for older computers or performance junkies. It is very well full featured and just by default should feel reasonably friendly to Windows users. K3b is KDE's cd burner which is really similar to Nero and is probably the best burner available for linux. On the flip side, KDE's IM client Kopete is still in very early stages and doesn't have many of the features (not stability) of Pidgin. KDE 4 is currently one of the hottest news items, and it will be interesting to see what will change with it. In the meantime KDE 3.5.7 is where the party is.

Gnome - GNU Object Model Environment - The Free Software Desktop Project
http://www.gnome.org

Gnome is a full featured alternative to KDE and the second most popular WM. It is built around the GTK toolkit so to have a logical Gnome desktop one should be using GTK-based applications. Doing so accomplishes two goals: reduces dependencies and the need to install extra libraries, as well as keeps the appearance of all your windows uniform. Luckily this is not a problem whereas there are plenty of GTK-based and GTK-friendly applications available in the Linux world. Gnome (full setup) comes with everything you should need for your computing, which includes games, internet applications, office applications, music and movie players and editors, as well as a boat-load of administrative tools. Nautilus is Gnome's file manager. It is very powerful and even includes features like an integrated FTP client and Samba shares browser. For CD/DVD burning you get GnomeBaker or Brasero. GnomeBaker is a very good CD burner but the menus can be a bit complicated for a casual user. It lacks a CD-ripping feature. Brasero has slightly more user-friendly menus and most of the same features. For internet use there is Pidgin for IM, Epiphany for Web Browser (based of Firefox's Gecko engine), Evolution is there to meet your email, address book, and calendar needs. Deluge is your BitTorrent client, and a whole lot more applications that you will have fun figuring out. Ubuntu is the most popular distribution to feature Gnome, though Foresight Linux is always on the cutting edge of Gnome development.

XFCE Desktop Environment - ...and everything goes faster!
http://www.xfce.org

XFCE can be called Gnome's little brother. It is heavily based around the same GTK libraries. XFCE is currently the best compromise available between a full features WM that has everything and the kitchen sink, and a minimal fast environment. With XFCE one can use anywhere between 70 and 200MB of RAM at idle, all depending on your configuration and how many applets you choose to run. Essentially this WM bridges the gap between Fluxbox and Gnome and does so extremely well. Some big differences between XFCE and Gnome include: Thunar file browser instead of Nautilus. Thunar is lighter and has fewer features, however it is still one of the best light file browsers available. XFCE has its own compositing engine (requires AIGLX). Whereas gnome relies on Beryl/Compiz for all the fancy eye candy, wobbly windows, and the now world-famous cube, XFCE has its own built in system for doing all that, it also runs lighter and faster than Bery/Compiz. And as all lighter WMs, you need to right-click on the desktop to bring up the menu, though a "start" button is available. XFCE is available in the repositories of most major distributions however Xubuntu and SAM offer a newbie-friendly XFCE experience right out of the box.

Enlightenment - Beauty at your fingertips
http://www.enlightenment.org/

This project is changing the way people think about WM. More commonly referred to as E17 (E16 for previous version), this WM is based on the Enlightenment Foundation libraries and has (a limited) selection of applications based on the same libraries. This environment is also very light and minimalistic, but unlike other lighter WMs that give up features and eye candy to be that way, E17 is choke full of great visuals. There is a debian-based distribution called Elive which acts as the poster child for E17 (also includes E16) and is a LiveCD (no installation required, but possible) so you can give it a try without committing to anything. Because E17 is so different from everything else even many seasoned linux users are often unfamiliar with this environment, but once you learn how it works you can have it all: great looks, and extremely fast performance.

FLUXBOX
http://fluxbox.sourceforge.net/

Fluxbox is highly recommended for older computers and for performance junkies you can't have their computer using more than 60MB of RAM while idle. Fluxbox is fast and extremely light. All this comes at a sacrifice however, this is a truly minimalist environment. To get to your menus you have to right click on the desktop, you won't find a fancy "Applications" or "Start" button here. In its basic look, Fluxbox is really plain, however some users have made it look quite nice with some effort (see the screenshot gallery on the website). To get a similar environment in Windows one may try bblean as a test drive.

note: there are several other less popular WMs available which I did not include simply because you won't come across them very often and they are generally more complicated to use, so since this thread is aimed toward linux novices, a more complicated WM is the last thing anyone needs.

Not a bad summary. Some of your RAM numbers are a bit off, but it provides the general idea.

Seablade

This deserves to be sticky!

good information on a topic that often confuses new users. I second the sticky vote.

one nitpick: KDE and Gnome are Desktop Environments, each having their own window manager (KWin for KDE), rather WMs themselves. Probably not overly important for your target audience, but it might good to at least allude to this fact.

XFCE is quickly becoming its own DE, too, I would say. It's not quite as robust as KDE or Gnome just quite yet, but I can see it heading that way.

sadly i see it too and polly don't like that cracker. XFCE is supposed to be a reasonably light DE, specifically to (1) be fast and (2) run on older hardware. if its gonna bloat itself up to gnome-size, whats the point?

I don't quite see it getting to be Gnome-size, though. Gnome is bloated because it's an ancient codebase and loves to coddle users instead of focusing on usability and lightweightedness. XFCE is newer code and applies a lot more minimalist design while accepting usability standards a little more. I like to think it's a compromise between Gnome and Fluxbox.

stickied, i'll be back to ask a bunch of questions =P

This is an excellent thread. Thanks abf for posting it.

Yay it finally got its sticky!

Good work ABF. Very helpful for me the n00b.