Snow tires - 2 or 4

It's very common for the rear of a vehicle to skid out when cornering (regardless of front or rear drive), resulting in less or loss of control. A rear drive pickup that is already light in the rear is especially prone to this phenomenon. Obviously front steering control is important, but it's been proven out that you need to keep the rear planted when trying to maneuver in icy conditions. And in slippery, icy conditions, it could be argued that the front has no more braking ability than the rear. In fact I know that by using 4 wheel drive and feathering the gas, I can often "pull" the vehicle out of a slide when braking is useless.