Re: Alfa 156 Radiator
Yeah, take the bumper off, remove the fan, then there are 4 screws holding the radiator to the vertical members on the front of the car. If you don't want to empty your aircon system (which I suspect is the case) you'll need to detach the smaller front radiator from the coolant one.
As for actually getting it out of the car, I think once you've undone those bolts it'll just lift up a bit, back towards the engine, up again and out. It's located with two rubber grommets on the bottom that mate up with holes in the radiator cross member (a black bit of metal that goes across the bottom of the very front of the car, between the two vertical chassis members). I removed the crossmember from mine but only so there was more room for the engine to come out - I doubt you'll need to do the same.
EDIT - In fact reading that back to myself I'm not even sure you do need to take the bumper off?? Probably makes it easier to get at things, though...