kinda depends on the data, if its calendar or such.
Nokia E61i, i'm assuming the phone gots a memory card reader.
Copy all files to memory card, insert to to your new BB.. grats files are transfered :o
regarding calendar / contacts, sync the nokia with pcsuite to outlook.
Then connect the BB and setup it to sync to outlook using desktop manager
Hope this helps you, if not, try to be more specific on what your going to backup