You are interested in making sure that either of the two cities can support another software company. As a result, you're interested in seeing how many other software companies are already located in Atlanta and Charlotte. What is also important is the current economy in those cities and how expensive each city is.
Below are some things to consider as you search for information online.
Here are a few links to information about these cities that you may want to look at to find answers to these questions, but you may find other sources of information as well. Try not to spend more than one hour doing research.