Hi I have a uk iphone 3gs on O2 but officially unlocked.

I as wondering if anyone knew of a sim card available in US similar to the O2 £15 a month unlimited text and data pay as you go sim.

I am in Orlando for 2 weeks in June and we usually buy cheap payg phones from walmart but would prefer to use our iphones.

Also would this affect my jailbreak as I have sat nav I want to use?

Thanks.