Winter snow tires should give you two winters of solid driving performance. Depending on when you have the tires put on and taken off, you could get 3 seasons (possibly four winters).
If you car is front wheel drive, the tires in the front will wear down 2x as quick. So to get longer life out of the winter tires, be sure to have the tires rotated front to back.
For the best prices on winter tires go to TireBuyer.com and get FREE shipping!