So I just sold my 32GB iPad Wifi + 3G on Amazon for $550 (winning!). I still have my unlimited data plan, and Engadget says I get to keep it. How do I go about protecting my data plan? Do I just have to sign out (or not sign in after I format the iPad) of my AT&T account, and then sign back in on my new iPad 2 that I'm getting on Friday? Or do I have to take the SIM card out and put that in my iPad 2? If I do have to take the SIM card out, what does the new owner have to do? Do they just go to their AT&T store and get a new SIM card? Thanks!