So I've been using my sluggish iPhone 3g for a while now, and a buddy of mine offered me his old iPhone 3gs. I'm not too tech savvy, but I'm curious how to go about switching from my iPhone 3g to his iPhone 3gs? Is it as simple as swapping the sim card? Do I need to go to the AT&T store? (For what it's worth, I don't have a sim-removal tool) Thanks I apologize if this question has been asked and answered to death (I'm sure it has!), however I couldn't find any relevant threads through multiple searches.