my $.02....
Tip 1) Don't depend on the last 6' of stopping distance to bring 75% of you momentum to a stop. That's how most people drive in stop and go traffic in the summer. The first slushy/icy day and even though they started applying the brakes early enough, they end up not having enough traction at the end to get the stoppin' done. Most winter/city accidents around here are little rear-enders, not the high speed skidding across the a bunch of lanes type of affair.
Tip 2) dedicated winter tires! (preferably with steel studs) But, be careful when braking. I've coasted through stop signs with glare ice that I could've stopped at with my studded tires (I could see there wasn't traffic coming). The reason I didn't stop was that in the rearview, I could see someone behind me who was oblivious to #1 above, and who wouldn't have been able to keep from rear ending me on their "all" seasons.
Tip 3) There's nothing magical about 4wd. Just because people can accelerate like summer under slippery conditions, doesn't necessarily mean they can maintain control on slick roads at summer speeds, or stop without a lot more stopping distance. So watch out for the 4x4's. When the city roads are icy, my fwd contour with studded winter tires and traction control will out handle and out brake most stock tired SUV's. Drop 12" of snow, well that's a different matter.
OK, maybe that was $.04.
Brent