I've looked around but I haven't been able to find an answer to this question. I'm beginning to wish I'd bought the 8 gig iPhone...and it just so happens that my wife's Razr is dying and she's in need of a new phone. So..the question is can I go out and buy an 8 gig iPhone, activate it with her number, and then swap SIM cards, giving her the 4 gig while I keep the 8 gig? (and don't think I'm some kind of jerk - she has only a couple gigs of music and no video - she's cool with a 1 gig Nano at this point so 4 gigs and she'd go crazy!) Would it be so easy as just swapping SIM cards? Or is there some other way around it that I simply haven't thought of? Any help would be useful as I plan on swinging by the Apple Store in the morning and I'd like to know all that I can. Thanks.