Driving in Italy

My best friend is going on a trip to Italy with her family, and they've rented a car. She'll be doing all the driving, and she's well aware that Italian drivers are notorious for being a bit... aggressive on the road. She was asking me if I knew if any road rules were vastly different than the US, and if anyone knows of a resource on the web for driving rules/laws in Italy. The only ones I've seen don't have a lot of information. (e.g. http://www.carhire3000.com/Worldwide/Italy/driving_in_italy.html)

...she's well aware that Italian drivers are notorious for being a bit... aggressive on the road.

I drove in the north of Italy and was surprised how easy it was.  I never felt like I was about to be run off the road or anything like that, the signage is standardized in every town, and the autostrada is well signposted as well.  I'd heard the Italians were crazy, but that wasn't my experience, albeit this was all between Venice and Milan; it may be different in different regions.