Gas and Oil Home Heating Furnaces - need advice for lowering energy bills

Details:
1. I live in Charlotte, NC. Summertime gets above 100 July/Aug, quite temperate (70-80) in spring and fall, winter gets down below freezing usually only at night, occasionally during the day.
2. House built in 1942. 1.5 story bungalow with a finished attic and an unfinished basement. Standard roof with a single dormer on the front. Finished attic has open stairway (nightmare for heating/cooling) with a small unfinished attic space on either side, accessible by a door. Also a small triangular area above that is not accessible.
3. Natural Gas furnace and AC unit, both Carrier, installed August of last year with a programmable thermostat. Old ductwork, though. Originally just central heating with 20 yr old furnace. Simply replaced furnace and added AC unit when I moved in. I paid a good $1000 extra to get a more efficient cooling system since I live in the south.
4. Natural Gas
5/6. Not sure what you mean by a boiler system - maybe I don't have one.
6. Residental zoning.
7. Programmable Carrier thermostat upstairs and downstairs. 2 zone heating/cooling system (single AC unit) with automatic dampers that force more cooling to the upstairs by closing off air flow to the downstairs. The whole house is 2000 sq ft, upstairs only 500 of that.
Other Info:
The insulation was really, really old. I pulled out all the old (YUK!) on one side of my attic and replaced it with batts of R-12 (I think). The floor had 6" joyces, and I used the thickest insulation I could. The walls were just regular 2x4s so I used the correct thickness (3.5") insulation for the walls.
I have NOT redone the other side of my attic - it has floor boards put down and I wasn't up for it. I will attempt this probably next winter when it's cooler.

Problems:
1. My upstairs would easily be 20 deg hotter than my downstairs without intervention. Maybe more. As it is, I keep my upstairs thermostat set higher than the downstairs (up to 85 during the day when I'm at work). The open stairway has to be a main culprit. It has no bend in it and at the top, there is just a railing around it such that I have a 10' x 3' hole in the floor for the cold air to fall downstairs and hot air to flow upstairs.
2. Energy bills are killing me. My natural gas bills for Dec/Jan/Feb were $180, $280, and $220 for my 2000 sq ft house. Not looking forward to this summer.

Here is my current plan, let me know what you think:
1. Re-insulate the other side of my attic - probably not until next November or so when it cools off up there. I'll put in a floor on the other side, move my junk over there, pull up the current floor, and remove/replace the insulation. Not looking forward to that.
2. Attic ventilation. I have an apppointment with a contractor next week to install some fans upstairs. I have a vent at the apex of my roof, but I think it may only work in that tiny upper triangle above the attic room, not the sides. The sides have zero air flow.

Any other ideas?

I'm going to come at this a bit differently than others, I did a lot of research before doing anything to the house we're in now, and my old one. A couple of things I learned; most heat gain is through the roof, not the walls, so work there first, and, FREE savings are better than PAID FOR savings, so I'm never going to used electricity (attic fans) to try to save electricity.

If you're roof is not really shaded, radiant barrier paint, can be painted on the underside of your roof decking, IMO it works better than the foil, under a really low slope roof it can be tinted and painted onto ceilings and it has had great effects for me.

I like ridge and soffit vents, and skin venting of walls where possible, to keep air moving through the attic space. Right now my attic is the same temperature as the outside air, and I'm inside working on the computer without the A/C being on, it's 94 outside!

I try to remove as many heat gains inside the house as possible, many if not most of our lightbulbs have been replaced with screw in fluorescents, saves electricity in use and (I think) reduces heat gain.

Maybe most important, it's in your utility companies interest to help you use less power, because it will save them the capital cost of builing new power plants. Many utilities will come do an energy audit on your house and find the biggest culprits of the heat gain, or loss in the winter time.
Good luck
Frank

At the bottom of this message is a www icon it will bring you to my site named Residential Energy Conservation. It is a compilation of many of the answers given to energy bill payers, much like yourself, over a 15 year period.