Don't know but I'm trying a clean insall of FC3 (It's what we use at work - I thought I'd rationalise) on my main rig.
The G450 is quite happily detected, so I tried the code found in System Settings -> Display. This allows me to define my second monitor, and resolution/colour depth, but it won't save it. (I click on OK and nothing happens, cancel works fine).
I'm currently running the full up2date, so I'm hoping that will cure it. If it doesn't I'm not going to be a happy bunny...