IPHONE 3G. Buy it in the states, then use it here in the Philippines?

Can i do that? Yeah I know, iphone is EXPENSIVE here in the philippines. I'm going to the states next month, so I want to buy that $199.99 iphone.

Will I be able to use it here in the Philippines? Let's say if i buy the "unlocked" one, will it be okay already?

Thanks thanks.