Hi Apple folks. I'm living in Japan right now, will be here for a few years. I'm going to look into buying the iPhone this Sunday. I will be here for a few years, so using it here isn't a problem. What I want to know is, will I be able to switch out the SIM card when I get back to the States, and will it be just as simple as that... ...don't want to spend the JPY 80,000 on the phone and have it be an expensive paperweight when I get back. Thanks!