I grew up in Thunder Bay, and those were BRUTAL winters. Major snowstorms, brutal cold and wind, and it seemed to last from early October until mid-April.
Now, in Ottawa, the winters are fairly easy-goin'. Not a ton of snow here (the most I've seen in my 6 years here has been about 25cm in one dumping and even that was rare). The biggest problem here in the Ottawa region is FREEZING RAIN.
That's why I recommend to people (who don't ski and travel mountain roads often) to buy witner tires that are better for ICE than anything else. We don't get a lot of deep snow, as Wing and others have said, but we get tons of freezing rain and that makes driving tricky.
Also, if you're getting a new car, spring for a clear-bra on the front. There's nothing worse than having to repair a bunch of salt/stone chips on your hood every spring before they rust. A clear bra will definitely help here.