Michael
It does not have to be a GTX 680m it just has to be a fairly current nvidia Geforce/Quadro chip.
At Ross many of the product specialists including myself use Macbook Pro laptops running windows in Bootcamp. I am on my second one the first was a 330m now I have a 650m and both ran great.
I would avoid AMD chips as they can cause some issues and are not officially supported. Also make sure the power management options are set to high performance. Many laptops switch between the dedicated graphics chip and a low power integrated chip when on battery power, you will want to force the laptop to always use the dedicated chip. Your battery won't last long and the laptop will produce more heat but XPression will be happy.
Andrew
#XPression