i am getting aiphone 3g without a contract, what should i do?

i am going to get a iphone 3G but i dont want the 2 yr contract with it
so lets say i bought a brand NEW 3G iphone without the contract( by paying more money)
do i have to activate the phone or something like that to use it( i want to use it like an ipod + text)??

i have a pay 2 go plan with att, so i want to use that with my iphone 3g. ( i only use the plan to text, i have a verizon for my talking on the phone)

To use that P2G SIM Card, you will have to unlock the iPhone 3G. That is only possible if you purchase a Turbo Sim. Google it for more results.

Some people have reported being able to just pop-in any AT&T SIM card, and the phone will work, but I doubt that could be true.