Sunday after our league discussion I ran a demo for two people thinking of getting into 40K. I had prepped for four people, but due to illness only two showed. We got a little bit of a late start so only managed to get through one of three potential matches, but given that everything was new not too bad.
We had 500pt armies facing off against each other. Andrew was interested in Orks, so he ran the greenskins. I originally planned on Orks vs. Marines and Imperial Guard vs. Chaos Marines, but the other player, Faith, was interested in Eldar and I figured Imperial Guard was closer to the feel (T3, poor saves on basic guys) than Space Marines would have been, so we moved armies around and she played the Guard.
Mission was a simplified Crusade, with one objective placed by each player and one in the middle, with First Blood the only secondary objective. Infantry only, no vehicles, independent characters, etc.
Imperial Guard man the line.
The first couple of turns saw the orks moving up and getting shot up by the heavy bolters and autocannons, with only the lobbas giving serious return fire.
The orks close in on the center objective, but this also gets them into lasgun and grenade launcher range. The lead mob gets wiped out.
Guard squads move up to try to secure the middle.
In the end though the lobbas and close-range shoota fire see off the guardsmen close to the objective and the orks grab the marker and the win, 6-4!
I think it went pretty well. For future demos I might even make the intro round only 250pts or so, like a squad of marines vs 20-30 guardsmen/orks.