That's a meaningless question. Do nothing? What pin? Do I think you are scared? Hard to say. Do you feel scared?
first of all, thanks for the links, I've got the idea with sleep, and I don't think I need it.
my question was related to the interrupt pins, I wasn't sure how they work, and as I was supposing, if I keep the pin low a lot it will just loop in the interrupt loop.
as Graynomad sugested, I will use the interrupts to count the "position" of the actuators.
In the meanwhile, I have ordered from ebay all my components. I couldn't find any relays around so I had to order them, ended up ordering them with the driving circuit since I might receive them late and not have time build the circuits that I need without the footprints (I haven't yet found an ebay chinese seller who would put a datasheet).
If they will come in 2 weeks I will probably remove them from those boards and place them on my own shields. I'll have to wait and see.
After I finish receiving the components I will post here what I have so people can give me their feedback.
One more question: what is the working temperature and the storage temperature for the arduino duemilanove? Is it the same as the atmels?