While much is online from the Census Bureau, researchers may need to go to a National Archives (NARA) location for microfilm. The National Archives at Atlanta is is in nearby Morrow, GA (5790 Jonesboro Rd., on the campus of Clayton State Univ.). Its visitor hours are Tues.-Sat., 8:30am-5:00pm. NARA's microfilm catalogs may be useful to peruse before a visit. The Georgia Archives are at 5800 Jonesboro Rd (also on campus of Clayton State Univ.). Visitor hours (as of 7/1/11): Fri. & Sat., 8:30am-5:00pm.
The Library subscribes to Ancestry Library edition database (from Ancestry.com), which has census population schedules up to 1930 - with names (1940 will be available in 2012).
NEW database: Social Explorer (library has one seat license for GT-authenticated users - please "sign out" after use.
Here are specific links to Census Bureau pages for Georgia: