I spend a lot of time in Switzerland and you do need (legally and for safety) winter tyres here. They're set up for it and it's very standard for local garages to store the set not being used.
They really do make a difference on ice and snow - it is extremely rare to skid on snow/ice unless you're trying to do so.
I'd bought a spare set of rims here with the thought of putting on some winter tyres but I understand they only make a difference when the temperature is under 7 degrees centigrade, otherwise they can be worse performing than summer tyres. As temperature here is so eratic, it is not like Switzerland where you can put them on in mid-November knowing that the temperature will be under 7 until the end of February, I am still deciding whether it's worth the cost. If you followed the 7 degree rule, you'd be changing them constantly back and forth.
If anyone is getting winter tyres, I'd wholeheartedly recommend Dunlop Winter Sport 3D. I must have done around 20,000 trouble free winter miles on them. Not noisy, no difference in mpg and the grip was very impressive. I reckon they still have 10,000 miles of tread left.
As I've said in other posts, I really rate the Conti Sport Contact 2 on my GTV. Quiet, good mpg and performance has been great. On my (new to me) 147, I have Bridgestone Turanza. I thought they were pretty poor on the motorway in last weekend's torrential down pour. Bur, I'm probably being unfair, as it is a car with a lot less roadholding than the gtv, is higher and although the tyres have been replaced within the last 25k miles they are not as new as my Contis.