yeah zombies is more fun with more people. It really doesn't work to well with any less than 3. Once we had an 8 player game which was nothing short of insane, but the ammount of beer we drank might have had something to do with it.
Its been over a year since I last played the game myself. I remember this was this one guy I would play it with on a semi regular basis. We got bored one day, so I actually made a map using all four sets from the original game and using Medieval to set up a regular city with a bridge out to the woods which took the players back in time ala Army of Darkness - it ended up being like an Zombie dnd game from hell lol. But it was cool.