If you're not looking for fancy wheels, the Sport Edition A7 is the obvious choice. They have been discussed at length in this thread.
For tires, everyone has an opinion, but any of the Performance winter tires from Bridgestone, Michelin, Pirelli, or Dunlop will fit pretty well with your climate. A little reading in the posts here will give you an idea of what guys have been doing.
I have accepted a new position at Tire Rack and am no longer in the sales department. firstname.lastname@example.org
is available to assist with M3 questions.