I have a 325xi here in Cleveland, where we get just tons of snow due to the lake.
I have to say, the 325xi beats my old front wheel drive in the snow. Great handling... however, as others have said, you have to be carefull of the confidence awd gives you. Here in cleveland it is mostly 4wd suvs that you'll find stuck in snowdrifts off the road, because they get arrogant and forget that enhanced acceleration does not translate into enhanced braking.
And of course nothing works on ice.
I don't use snow tires, my all seasons work great here.