Hi!
I use Openbox
http://www.icculus.org/openbox/ and I would never change back to kwin. It's the only windowmanager which is completely supported in KDE 3.1, so you have 3 opportunities to use it:
1) as a complete replacement of kwin via editing startkde.
2) stand alone and starting kdesktop (this gives you the KDE Desktop with Icons and Drag&Drop
3) stand alone and only starting kicker. This is what I prefer, because I like the original root window with all its possibilities rather than the 'overpainted' KDE background. With this setting I can use the mouse wheel to change desktops, a feature I really miss with kwin.
Other advantages are the keygrabber which gives you much more flexibility for hotkeys than the similiar KDE feature, a complete integration of KDE 3.x and GNOME 2 panel applets and WindowMaker DockApps at the same time, the possibility to hide the window decorations for some applications, the smaller footprint, the good xinerama support and ... much more.
You should give it a try.
Thomas