addolcitore o Calcificare?

Not a bad idea to put one of these in, in my opinion - at least if you have water as hard as mine (also in Umbria). It could well pay for itself in keeping your boiler and washing machine alive for a few extra years, not to mention eliminating the boring chore of weekly cleaning your shower heads and replacing the aereators in the taps every year or so! You are right, Italian ones are rather more expensive (and rather more sophisticated, and much more automated) than the middle range UK ones. If you are going to rent out your house then you have to jump through various hoops about backwashing etc., and it maybe that UK models are not homologated for these applications, (but then again, the Italians usually soften the kitchen tap water which is a bit silly: if you have straightforward comune water coming out of that tap, what's the fuss about the odd bacteria in the softener?) However, if it is just for yourself, why not get a cheapo from the UK if price is a big consideration. They usually plumb in on flexible pipes - the metal sheathed type of pipe, often 3/4". Just about a DIY job if you rig your plumbing so it's doable.

Magnetic ones apparently work but no one knows why. This sort of thing: http://www.emwc.co.uk/Details.asp?ProductID=1618