I have two cards in the system: 6600 (monitor is connected to it) and 8500 for experiments.
Driver provided with CUDA 2.0 does not support 6600 (what a surprise … initial version of 2.0Beta2 had the same problem!). Installing the 2.0 driver - and watching at the beautiful black screen after reboot (as 6600 is not functional at all, windows does not even see it).
Definitely, it would be great to fix it ASAP!