Connect the burner to the iBook, via the Firewire connector, and insert a CD with information on it. Any CD will do.
If it mounts on the desktop, then the device is actually recognized by the system.
Now, go to the Apple menu and choose About this Mac. In the next window, select More Info.
This will bring up the Apple System Profiler. Choose Disk Burning from the choices on the left and in the RH window you will see a list of available burners. Click on the Sony and if the device is support for DVD burning from the system, it will say Supported. If not, then you will have to use a third party DVD burning software like Roxio Toast Titanium. It does not mean that you cannot use that burner with the iBook, it just means that you cannot burn directly from the system to it. ie, from DiskUtility.

hope this helps