I'm in the US with AT&T and a current 3G. My 3G S will get here someday soon (2-day shipping seems to mean "we'll still send it whenever we feel like it" to Apple), and I'm foggy on how to switch to the new phone. I've never had a SIM phone before. Do I take the old SIM out and put it in the new phone or just plug the 3G S into my computer and it will say "do you want to activate this phone instead of your old one" (or similar)? Added to this mix, I want to keep my 3G and use it as an "iPod touch" for gaming and jogging and such; do I just leave it in airplane mode for that to work, or is there some trick to it? If someone could spell out the steps for doing this, I would be very grateful.