rim6720, Welcome to PinStack.
For the upgrade to 4.1, you can use any of the appropriat carrier OS for your BB. Your Carrier might complain if you have a problem that requires repair or replacement though. If I were you, I would call them and ask for the link to their OS Download site. As to reinstalling all the settings. If you do a backup/Restore during the OS update, all should be well afterwards. There may be some of the OTA installations that might have to be redone, with the 7100, but I haven't had that problem. You will have to resend all your service books, but usually that can be accomplished by going to Options/Advanced Options/Host Routing Table and from the Menu, selecting Registor Now.
Let us know if there is anything else we can do to help with this problem or your BB.