My understanding is that freeze-thaw cycles don't affect granite, unless the granite is cracked, or water gets under the granite. So, proper installation is critical.

If you're up to doing it yourself, you may get help here:
Bricks, Masonry, Asphalt and Concrete
http://www.doityourself.com/forum/bricks-masonry-asphalt-concrete-3/

If your not interested in doing it yourself, you need to make sure your getting good advice from an honest contractor.
You could join Angie's List to find a reputable contractor in your area. I join Angie's List periodically for 30 days -- to keep the cost down. I cancel my membership within the first 30 days because I really don't have a need for an annual membership.
http://www.angieslist.com/