Your question is obviously complicated. We dont know for sure what ATT will tell you, your best bet is to talk to them. My gut is that in order for you to get an iPhone compliant SIM you need an iPhone plan, and they might still try to nail you on the 2 years. But talk to them and maybe you'll work something out. None of us in this thread work for ATT (AFAIK) so we can't guarantee what they'll do or any relative merits and cons of the requirements they place on the plans.
let us know what happens!
let us know what happens!