Motors, L293D and Arduino ?

What is the maximum number of L293D that i can connect to a Arduino Duemilanove ? My project needs me to run 4 motors. Is it possible ? If yes then how ?

Typical setups utilize two PWM outputs and two digital outputs per L293D, which gives you control of 2 motors.

Question: Do you need completely independant control of all 4 motors? If yes, then you'll need 4 PWM outputs and 2 digital outputs to independantly control each motor output on 2 separate L293D motor drivers.

If this is a quad rover, then you really only need to independantly control each 'side' of the rover, and you can use just two PWM outputs and two digital outputs to control both L293D motor drivers.

Either way, the Arduino has more than enough PWM outputs and digital outputs for the setup.