What is the use of a dual 450 GHz. It wil not make my Cube much faster. I would rather install a single 1.2 GHz GHz CPU that would not need a fan as far as I understand.Nvm, it was actually dual 450, but that's only a 50mhz difference, so you could always OC to get a dual 500 cube.
It uses the 7400, just like the Cube.
http://www.xlr8yourmac.com/systems/cube/dual_g4_cube/dual_g4_cube.html