Nah, we had the other way around, of course - games (or NWNx modules) created after D&D modules, and even novels for some modules/games. But I don't know about a NWN or NWN2 module.
I don't know whether that wouldn't be problematic, anyway: Did your players play the game? If so, they'll know about the plot, and you'd have to change things around, anyway.
And all those NPCs would probably not fit too well into a normal module, either (all those henchmen are good for single player computer games, but I don't think they're good for a P&P game, unless you put them in as standard characters for players to use)
Still, it might be a good one.