Annie ask you to restore to Custom firmware created by Snowbreeze 2.0.2 is because , it will preserve your baseband.
Download ireb 4.1 and follow the instruction to put you into DFU mode and then restore to custom firmware of 4.1 built by Snowbreeze 2.0.2.
If you have the official sim, then uncheck activate my iphone while creating the custom firmware. Use your valid sim to activate it, then you won't have any issue
Last edited by iYeow; 10-16-2010 at 10:42 PM.
Reason: Automerged Doublepost
The jb PDF guide isn't up to date for 4.1. I made the edits and adjustments in the original post up top. Just follow what Yeow said and you'll be fine.