I will be traveling to Europe in July, landing in Frankfurt am Main and traveling through Germany, Switzerland, Austria, and France. I just ordered an unlocked iPhone 3G off eBay. I'd appreciate any recommendations for the best place to purchase a SIM card in Frankfurt once I get there. Or, given I am traveling through several countries, is it better to go ahead and purchase one of the "world" Sims Online before I leave? I also have a 3G iPad I want to purchase a Sim for. Thanks for any suggestions.