1.2ghz 7457 G4 in one, 1.0ghz 7455 G4 in two others. I've chromed one Cube - that one actually sold as soon as I showed it to a friend.
In one, as mentioned before, a GeForce3, the chromed one had a GeForce2 MX, and the one in my footer has the ATi 9700. That extra space by the Powerlogix...