Now I know u may all be technophobes
but its not difficult to jailbreak (kinda hack) iphones a to get added functionality and b be able to use it on a different network. I have done it multiple times.
Jailbreaking gives you access to Cydia which is like a hackers appstore where you can download loads of stuff like 3g unrestrictor which lets you use skype on the move (therefore reducing call costs significantly) and slingplayer to watch tv on the move (if u have 1). Here is the best site for info I belive www.quickpwn.com
but for Iphone 3gs or even just 3gs software you want to use redsn0w redsn0w.com and for unlocking its ultrasnow that you want from the same site i think!
(even on ipod touch Jailbreaking gives alot better functionality!!