I drive an AWD Subaru WRX wagon and I always have snows on them as soon as it starts snowing. All you tough guys can keep riding your all seasons until a real storm hits and you're car is about as useful in snow as a fish out of water.
On Christmas day in 2002, my wife and I were travelling back to Rochester from NJ when the biggest snowstorm to hit Scranton, PA hit. There were so many cars stranded on the side of the highway it honestly looked like a parking lot. My wife used to drive a FWD Accord, but because we had snow tires, we were able to keep plowing forward along with the only 2 other vehicles that could keep moving (Nissan Xterra and Grand Cherokee...those owners were also smart enough to have snows on their SUVs). We finally pulled off the highway because they put roadblocks on it to stop people from going any further.
The Holiday Inn we stayed at was up on a huge incline. I saw an Audi A4 try to make it up and slide backwards down the hill. My wife wasn't willing to try it and just wanted to make the hike on foot, but I took the car up slowly and we made it without any problems. Keep in mind, this is a FWD Honda Accord. On a 4WD or AWD vehicle, having snow tires practically makes your vehicle a tank. In regular conditions driving slowly with All Seasons will be fine, but when the stevestojan hits the fan, you'll wish you'd spent the money.
For those interested in purchasing them, my wife was running Bridgestone Blizzaks. They're not too expensive and obviously worked great for her. I run a set of Nokian WR's...might pick up a set of Nokian Hakka's this year.
http://www.nokiantyres.com/
They know their winter tires.
/no, i'm not a tire salesman