Hey all. I have a question which I'm sure has been asked to death!! Buuut I am currently an At&t customer. I have the Samsung Eternity for a little over a year and I am going to buy a used iPhone 3g from ebay. Will my At&t sim card work in the iPhone 3g? Also, I have been reading about the whole iPhone activation process. Not familiar with it. Since it's a used iPhone and already has been activated, how would I then activate it for my use? I'd like to use itunes to add my music and apps! -- I have unlimited data for $15 a month and I added the 200 txt msg for $5. Can I get away with it? 