I used to live in a 1500 sq ft house (built in 2001) in the southern part of Georgia. I did run my PC 24/7, but I had compact fluorescent bulbs in nearly every fixture (including outside lights).
January was usually the highest energy consumption month (I know I've hit 1200 kWh), but the summer wasn't far behind. In the summer, the rates are higher and the bills were significantly more.
Why so much electricity in the cold months? In that area most houses use heat pumps for heating (no natural gas infrastructure) with electric heating elements in the unit for when the temperature is too low for a heat pump to work (below 40F?).