I know I am quite late to suggest you, but my suggestion will help you in the future, I recommend you to buy Bridgestone Blizzak DM-V2, I also use this tire, These are excellent, Soft rubber compound grips in the Cold temps, I purchased it from Reecoupons.com at a reasonable price too. Plan to put on the All Season when warms up.
I just purchased a new 20109 MKZ and plan to buy winter wheels/tires via TireRack this fall. Had Michelin X-Ice on my last car and they lasted a really long time, so I'll try to find them in an 18" size. In Cleveland Ohio, they put down enough salt to cover the moon, so winter wheels are a must to keep the factory ones from corroding.