US iPhone on a trip to Europe

[AlreadyGone]

I live in the US and have a first generation iPhone;
I'm going on a trip to Europe: Northern Ireland, Germany & the Czech Republic.
What's the best (and CHEAPEST) way to use my phone over there?
Would I need to buy a SIM card in each country to avoid roaming charges?
Can I buy one before I leave?
Thanks!

 

[Moi un Mouton]

Well, a two part answer:

- if you want to use a local SIM card, you will have to unlock your phone, which is pretty straightforward for a 1st gen, lots of instructions on the Hacks forum here for how to do it

- if you are going to use it to call locally, definitely buy a local prepaid SIM card in each country, but if you are going to use it to call the USA I'm not sure you'll save anything as international calls are generally very expensive either way. If you want to use it for internet, it will normally be cheapest to do that by wifi whenever you can, from hotspots in hotels, stations, etc, rather than by GPRS/Edge