Sprint is a CDMA carrier and that phone is a dual-mode one which works in the US on CDMA frequencies and in Europe on GSM 900/1800 so the phone should not be a problem, hoping it's not sim-locked (but CDMA doesn't use sim cards, so I suppose it isn't!

).
Anyway it's not important to know which provider you use in the US if in Italy you are using and Italian one with its sim-card.
As I already told him on PM, you can find all the information about Italian prepaid plans, in English, here:
http://www.prepaidgsm.net/en/italy.html