I am making an online role playing game, like everquest or whatever.

I have come across a problem in that I am not sure how to make the npc's (non player characters.

My problem is I need to have it so the npc's are similar to other players in that move and opperate on all players' computer's the same. So lets on player 1's computer, an npc is walking around at a some coordinate in a level, on player2's computer, that npc is shown walking around on his computer the same as on all other computers. So basically what I need to do is make it seem as though the npc's are real players themselves, acting the same for all players, and not unique to each player.

One idea I had was to make it so all the npc's run on game host's computer, and then their information(coordinates or whatever) is sent to everyother player, however I figured this could really lag bad if I had like thousand's of npc's information being sent repetitively.

Any Ideas?