Rel
Liquid Awesome
I'd give them some pre-gens. I'd even write-up a bit of a background for the pre-gens. Make it like a con game. Provide strong archetypes that are easy to get into. Print out powercards and character sheets before hand. You want to get to the game as quickly as possible.
Because you control to an extent the pre-gens motivations and the story you should be able to come up a compelling story and combat.
Just don't waste time with 1 PHB trying to make 4 characters. Picking and writing in all those powers will take forever and will really turn them of the game. While making characters is less of a problem than with 3e it's still a problem. Promise me you wont let them make their own characters.
I agree with this completely. Don't have them make their own characters (which will feel more like doing their taxes) and get right into the fun of the game. Once you've got them hooked then you can give them the option of making their own characters (or maybe keep playing the ones they started with).