All-seasons are never good enough for winter. Get some new tires, and stop being a bitch, as the poll option says.
Seriously, you can have a little bit of both worlds with all-season tires, but they just don't handle either extreme. You'll do fine on a day with a temperature of 40-80 degrees, but better tires are a necessity by the time your local grass gets frosty or on the hottest days of the year.