As I bought a new Bold 9780 (great phone !), I am planning to give my old Storm to my son. He has a different provider, in the UK.
Am I supposed to delete all service books on the Storm ??
He will use the device only for making calls and texting, initially. Only later on he will get a data plan, for browsing and checking his email account.
Thanks to all those that will reply.

It doesn't matter if you delete them or not.
Without a data plan, even if the service books are present, they can't be used.

Once you have a data plan, new service books will be sent to the handheld automatically.

I would do a wipe to remove all of your old data.

By "wipe" you mean wipe out just the service books, I assume. Not the applications, etc..
Can you confirm ?

See this in the FAQ: How to wipe ALL personal data from a BlackBerry device? - BlackBerryFAQ