For those "on the fence" in Winter weather regions, your tire choices can have a major impact on the outcome of regular day to day driving and your stress levels.
I had a "newish" GTI that was my DD, it received hail damage during a major thunderstorm around August of 2006. Some insurance money came back and instead of fixing the hail damage, I decided to repair a wheel bearing and put a set of sticky low-profile summer compound tires on the car, prizing handling response and absolute grip at that point in my life over anything else (oh to be VERY young, and dumb, again).
The following Thanksgiving night we had a cold snap and average temps went from about 53*F down into the low 20s. I learned the hard way while driving out to a friends house for a "Thanksgiving" house party while temperatures were dropping that summer compound tires quickly turn into hockey pucks even during routine driving procedures at those temperatures. I entered a road construction zone and attempted to make a corner at the posted speed limit (or maybe even slightly below it, I had noticed some traction issues prior to being at this point in my drive). Unfortunately my car ran out of grip, I ran out of skill and I lost control of the rear and hit the concrete barrier and went vertical and rolled, totaling the car and seriously injuring my confidence in my ability to drive a vehicle safely for the next year or so (I was pretty hard on myself at the time). I had a 12 pack of beer in the back of the car that flew past my head and shattered all over the road so I looked like I was drinking while driving too. It was a bad situation, but a well learned lesson and I was not physically harmed other than some bumps and bruises.
Fast forwarding to owning a used Audi A4 with three mismatched tires (including model, brand and wear levels) and Winter approaching again within a month or so, I went into heavy research prior to purchasing replacement tires for the car. It was regularly reported in the German autobahn tire testing articles I could find that a Winter tire was rated to have superior grip, even in dry conditions, compared against all-season compounds where the average temperature was below 40*F. Typically this was due to the tire being engineered with a higher silica content and a specific heat range for maximum grip falling around 15-20*F with a roll-off both above and below that point having higher grip than the roll-off of an all-season in that same temperature range.
With Winter tires not only does your static traction increase during straight line maneuvers (acceleration and braking) but they also have a large impact on stability at speed as well as maneuverability during emergency procedures. I don't condone driving outside of the control limits of your car or personal skill, but with Winter tires on the car I am typically much more comfortable maintaining "highway speeds" in less than stellar road conditions because I can feel that the car is planted and stable, especially compared to how the car drives on OEM All Seasons or Summer Compounds (God help you, may you have my prior fortune of no serious injury). Since my accident and change in tire strategy I have had the opportunity to "demo" my tire choices during snowstorms bringing people home from birthday parties or shuttling relatives to holiday parties and the like. People are always amazed at the difference the Winter tires make when the roads are slick/slushy/show covered. All the while watching SUVs fishtailing in 4x4/AWD mode on all-seasons and going into ditches due to their inflated sense of Winter driving capability.
Also, not to throw most drivers under the bus (or anyone who hasn't completed a Winter driving safety course), but most of the (non-motorsports interested) people I have ridden with don't seem to pick up on the handling changes that occur prior to a loss of control and are in an accelerating yaw rate before they attempt to make corrections and the accident is basically inevitable at that point unless they have a LOT of empty road in front of them. Winter tires give you extra time to regain control of a bad situation or help you prevent one from occurring in the first place. Having that safety net available could mean the difference between a police/hospital phone call or a happy/excited call from your significant other stating how he/she was able to avoid an accident successfully thanks to your foresight and preparation. I don't want to take the risk of losing the one I love because I was unwilling to spend some money up front.
Sorry for the long post / life story / rant but it's something I feel strongly about and try to promote amongst the people I care about whenever possible.