Well, I did a fresh install of the OS when I got the new motherboard. It installed fine with 2 cards, but to turn it off I had to hold the power button down.
Its a little werid, because I had been wanting to try an SLI setup with my 460, but I don't know if that will be the case. It might be something in the BIOS or something.
The driver package 306.23 is installed for both cards.