Open source window managers on Mac OS 10.5.x? [View all]

Not sure if I should post this in the Mac forum or if it'd be better here, but I am dead tired of the standard Mac OS window manager and want to use an open source alternative. On top of that, my MacBook is old and has seriously limited system resources. I was thinking something like Enlightenment (if that's still in development, it's been years since I last really tinkered with open source software) or LXDE would be nice, because they're going to be pretty and useful, and also easier on my old computer.

Has anyone in the room ever replaced the default Mac OS X window manager before? Is there a good reference out there on how to do it? Besides LXDE and E, are there any other favorite WMs?