I know a lot of people don't think the S2000 is good in the winter, but with the right tire choice they are a fun car in the snow.
If you live in the snow belt, the correct choice of tire is different than if you live in St. Louis where you can get away with a tire like the Dunlop Winter Sport or the Michelin Primacy Alpin PA3. On the other hand if you are in Buffalo or South Bend, Indiana, I would suggest the Bridgestone Blizzak. In the worst conditions they offer the best traction that I have experienced.
Whether you decide on a Winter Tire and Wheel Package or simply switch tires back and forth, consider winter tires as the best insurance you can buy. The way I look at it is I am making my other tires last longer and with winter tires on the car for the colder months, I can put even higher performance summer tires on the car for the rest of the year.