Be warned, Alfa's are prone to breaking down and if I am to believe the ToPGear survey, the dealers tried clients as manure.
They are "nice" cars, though. practical and lots of fun to drive. Basically, Alfa as always.
Top gear survey (which is UK only and from the last few years, so could be relevant to you) rates Alfa 156 as such:
Engine/Gearbox Reliability 3/5
Electrical Reliability 2/5
Brakes/Suspension/Steering 2/5
Fit/Finish 3/5
Squeaks/Rattles 3/5
Performance 4/5
Handling 4/5
Comfort/Praciticalty 2/5
Customer Care 2/5
Ownership Costs 2/5
http://www.topgear.com/content/features/stories/2005/11/stories/01/10.html