Speaking as an absolute newbie, I've found that you can take apart Campy with a screwdriver if you are very very careful. With Shimano, the only way to dissasemble is to bang it again and again with a good-sized hammer, and then all these little springs and nuts and trolls go flying out all over the room and, inevitably, one of those little trolls rolls onto my bikeforum page and starts growing, sometimes six, ten pages...