Sure blackbox, fluxbox, windowmaker, openbox, ion3, wmii, and so on are all fast enough window managers for a lightweight desktop. I have used them all for quite some time (except for blackbox).
I'll give my opinion on them. Not that it matters much, but maybe it'll help someone to make a choice. But what matters most of all is that you should really try the window managers yourself if you want to know what's best for you.
Fluxbox:
I used this one a long time but I found that it's menus are a mess. Look at openbox and see what I mean, it's much cleaner. But fluxbox has good and easy to configure config files. With fluxbox you can use dockapps, you can find many of those which give you what you want. But that just increases the messy look of this window manager in my opinion. Fluxbox's panel also isn't very feature rich...
Openbox:
A very clean wm. It's nice in combination with pypanel. It has a nice configuration program called obconf.
I found that the menu file is made in xml though, so it's very complicated if you need to hand edit. Openbox is good looking.
windowmaker:
strange but fast. I tried to use it but never got used to how it works.
ion3:
it's focused on keyboard users. The default configuration isn't very nice but after some configuring you can get a nice and fast setup. But it has terribly lua script config files. It takes more time to edit them and every new release of ion will probably be incompatible with the previous version's cfg's. It's also too strange to learn it too anyone who doesn't want to waste time on a computer.
wmii:
also focused on the keyboard. Has nice default keybinds. But it's quite buggy and not very fast (I'm talking of speed on a p1).
It has some nice features like the program launcher.
But has no mousemenu's at all, and the config files can be quite difficult.
Ratpoison:
Very fast. It does only work with the keyboard. Has a relative simple config file, good default keybinds if you have a qwerty keyboard. I like it in combination with screen but I would never let any newbie use it. It's great for keeping yourself focused on a task because it shows programs in fullscreen.
Memory comparison:
Here's a little comparison of how much memory the wm's use when I look at the numbers given by "ps aux":
1,4% ratpoison
4,8% ion3 (without the status bar on the bottom, which probably adds around 1 %)
5,8% icewm (with silverxp theme it uses 1% more, without the cpu and memory status it uses 1% less)
6,2% openbox
7,5% fluxbox (the newest devel version)
7,8% windowmaker
8,9% wmii-2 (with the new small rc shell)
14,5% ede (only eworkpanel and edewm, using desktop icons ads 7%, starting something from the little command line on the taskbar adds 5% for some weird elauncher program until you close the app you started with it)
These are percentages from the amount of ram I have: 64MB.
They are relative though.
For example openbox shows using less memory then fluxbox, but fluxbox reacts faster then openbox.
Overall ratpoison, ion3, icewm, windowmaker and fluxbox seem fastest reacting.
Conclusion
I found icewm best considering ease of use for newbies (windows users), being powerful for "powerusers", looking quite good and being fast. Icewm was one of the window managers I tried latest, I never really gave it a try at first because it looks so much like windows. I can imagine many others have the same feeling. But icewm is much more then a windows look a like.
It has great commented easy to edit config files, ctrl+alt+space commandline function, a great full screen function, very good keyboard shortcuts and a cpu, memory and battery monitor.
Here's a nice review of icewm where I learned some stuff from:
http://www.osnews.com/story.php?news_id=7774&page=1
A gui tool to configure icewm would be nice, there's a good menu editor called iceme, but programs like icepref only messed up my configuration.
Still it's possible for newbies to change the theme easily using the menu and with iceme they can edit the menu.
There's not more that should be changed with sane defaults, in windows I almost never see anyone needing to change the default setup there either.
greetz,
gunnix
