You may not have to take the car to the dealer for reprogramming. IIRC there is a reprogram/relearn sequence you can do yourself.
Is the security system Passlock 2? Saw this on WIKI answers.com.
For the Passlock 2 system, put the key in the ignition and turn the engine over (the car should not start, if it did you are done), turn the key to the ON position, let it set for 10 min. The security light should be flashing. After 10 min. the security light should stop flashing the car is ready to learn the new key value. Turn the key off, wait 5 seconds, and then try to start the car.
Hope this helps.
