I have only been regularly commuting by bike since March of this year, but have been riding in Atlanta since the 70's. Like RonH said, Atlantans love their cars. If you live and work inside the Perimeter Hwy (I-285), getting around by bike isn't too bad. There are a lot of neighorhoods streets that interconnect, so if you have the time and desire to find new routes, you can stay off the busiest streets. DeKalb and Fulton also have a speed hump program which allows neighborhoods to decide by majority vote to install speed humps (speed bumps) to keep car speeds to 25 mph. Remember that metro Atlanta is a huge, spread-out city. It is common for car commutes to go to 30 to 50 miles one-way. But don't let any of this scare you off. Altanta has some great hills (work that heart!), a lot of trees for shade, a few bike paths/lanes, weather so you can ride year-round (hope you like warm weather, they don't call it Hotlanta for nothing!), and some really nice people. My wife, son and I ride everyday to his school, and many times drivers have given us the right of way. If probably helps that we are obviously a family out riding. When I am out by myself, I seem to find the idiot drivers more easily.

When you find out where you will be working, give us some more info and I'll bet the commuters here will be glad to help out.