Freenx is awesome! I'm having trouble with a yellow mouse though. Argh. After trying to debug it via Freenx client, I've determined it is caused by quartz-wm. I'm therefore trying a new window manager within X11.app, specifically xfwm4. I'll also install sawtooth for use with Gnome desktops. To do this, I'm installing Fink.
It had nothing to do with the window manager at all, but was a bug in X11 on the Intel Macs: