Iphone noob question about sim & activation

[aphexacid]

I wanted to know how i'm supposed to go about activating my iphone when it comes tomorrow...

I've got at&t

Do i plug the iphone into itunes, with the included sim and avtivate, and the included sim becomes my new active one?

Or am i going to take my current sim, put it in the iphone and then activate.


I bought my girlfriend an iphone last year, but i dont remember how we did it.

thanks!

 

[aphexacid]

Anyone???

What are you new 3G S users doing? You using your old sim, or does the new sim get activated?