christian is right, snow tires won't give you full traction in the snow. i don't know about x-ice, that's new, i've had michelin arctic alpins and blizzaks and i don't regret getting them.. they help a lot and i don't get stuck anymore.
i think they do make the biggest difference stopping, and accelerating from a stop. on corners i still slide out a little with my blizzak's which is controlled and is fun.. but to be safe i still drive carefully in the snow as if i had all-seasons if you know what i mean.
Also you can get LSD and it'll help on those turns.
