Here are a bunch of links that are concerned with violence in games. Most of them support the idea that game violence relates to violent behavior.

Erin

On Game Violence

This is the official rating system, which must be stated on every game, and
in game guides, too.
Rating System

questions the research
links to a lot of
articles
online mag
your viewpoint
from
20/20 show
research paper
comparison
usa today
research article