I've got a second set of wheels with winter tyres fitted which come out each winter. I thoroughly recommend them to anyone more for the safety when it comes to turning and braking than anything else.
My car is Quattro, so generally speaking, its pretty good at getting going... the problem comes when trying to stop from anything other than about 2mph. With the winter tyres on the ability to turn and brake is so unbelievably different its hard to believe we're allowed to drive on ice/snow without them - given all the other laws and regulations in the UK.
The tyres I use are Pirelli Sottozero S2's. Being a 275/35/20 fitment on my car (I can't go smaller due to calliper clearance) the choice of winter tyres is very limited.