Updating from 4.2.6

I have a jailbroken Verizon Iphone 4 using IOS 4.2.6. I was planning on updated to IOS 5.0 then jailbreaking again. I heard that doing so my lock my phone when updating to 5.0. Is this true? I am also getting a message that tells me new carrier settings are available. What should I do?

Thanks x 2

Ok will do