I'm not in the snow belt, but I make sure to take my '06 STS AWD out when it does snow. Car does really well. As previously mentioned, use your brain first.
First week or two of owning my STS, I got a little aggressive during a light snow, tried to pass people around a corner, back end came out from under me, had a moment when I was certain I was going to wreck my new ride (and look like a mega douche idiot), but then the stability system kicked in and it was like it magically straightened itself out. Don't recommend it though, it's hard on your heart (and on your ego).