The Ubuntu Tips blog suggests using the XFCE window manager as a replacement for Compiz and Metacity in GNOME. From the original post:

If you can’t get compiz to work on your machine, or you just to run a compositing window manager with shadows and true transparency without having to deal with hangs and memory leaks, you can run XFCE’s window manager, xfwm4.

This sounds intriguing to me, but I think I’d miss my cube. The full story has instructions!

Full Story: How to switch to xfwm4 (XFCE Window Manager)