This article is from the Italy FAQ, by Gianluigi Sartori firstname.lastname@example.org, Paolo Fiorini email@example.com with numerous contributions by others.
A video-game unit bought in the U.S. outputs a NTSC signal and will
work only with a NTSC or multi-system TV. Cartridges, however,
contain only software and should work fine.
Cameras sold in the U.S. often have different model names than those
of identical models sold in Europe. The Italian distributors will
often not honor a U.S. warranty, unless the owner can prove to be
a citizen or resident of the U.S.
See also question 8.1 in this FAQ section