I'm thinking about buying the Arduino Duemilanove. I want to know if you can stack this board with a motor driver shield and a prototyping board shield and if so can you stack them in any order?
It depends on the physical construction of the motor shield and the prototyping shield. If the pins coming up from below are connected to connetors above, you can stack them.
One motorshield I know of doesn't use all pins and have an empty space over some of the connectors. Just put some raiser connectors in those to stack them too.
The stacking order is of no importance as the pins are just connected through. However you need to be careful about resource conflicts between the shields and your power supply.
Korman
youc an't stack anythin on the motors shield most don't have the stacking headers