No problem, as Andrea said, you don't need to go to a TIM shop, maybe you just need to understand Italian, or ask an Italian friend for help. And of course you need credit on the simcard.

Via 4916 you can change the italian language with the english (or german) one :)

Thanks everyone! :)

Only one thing David: consider buying a Wind prepaid card instead of TIM, you could have some important advantages:
- ? 20.00 per month instead of ? 25.00
- 1GB of data to use 24h a day and not only after 5pm
- less people use Wind, expecially at the Olympic games, TIM's net could be overloaded, and data will probably be really slow (it's already slow now, far from Turin!); Wind GPRS performance is usually better than TIM (but TIM has EDGE) in normal conditions. And in Turin those days there won't be normal conditions.
Wind has good coverage in Turin and also on the mountains where the games will be, as well as TIM and Vodafone.