What you need is your PUK and PUK2 codes. Those are the "PIN unblocking codes". They will allow you to reset your PIN and PIN2 codes.
Your provider should be able to give them to you over the phone (at least Cingular does).
On my phone (v400) I can reset the PIN code by keying in:
**05* - PUK - then OK
You will then enter your new desired PIN1
**052* - PUK2 - then OK
You will then enter your new desired PIN2
Worked like a champ!
BE CAREFUL - if you enter the wrong unblocking code 10 times, your SIM card is supposed to be permanently disabled.