do i need a new sim card

3 years ago i bought a phone from cingular now att.
it was a pay as you go plan.
we have not used it in the US since april 2008.
now we want to start using the phone again in the US on a pay as you go plan.
do i need to buy a new chip?
or just sign up for another pay as you go plan.
we cannot have a monthly plan.
thanks

PS roaming? does it matter if i buy the plan in WA or where we will be for a few months CA?

...Bump to AT&T

And to answer your question, all you would need is a new SIM card, available at any AT&T store.
Cingular phones work with no extra programming for AT&T.