Might sound a bit dim but is it possible to have a simple explanation of Drive By Wire. Have I got it or not. Advantages and disadvantages? 
Basically Rob -
One earlier prefacelift cars (like yours), you press the thrrotle pedal in, and it pulls a cable. This cable opens the throttle bodies, allowing the air into the cylinders. The ECU knows the throttle position, from the throttle position sensor, which senses where the butterflies are.
On later cars, there is no cable attached to the throttle pedal. When you press the throttle on one of these cars, it sends an electronic signal, which talks to the engine ECU, and in turn operates a little motor contraption on the throttle body, and then opens it in the same way. This is DBW - Drive by wire. Slightly more effiecient than a cable driven system.
This has many advantages - including no need for an actuator / cable for cruise control

Does this answer your question?