Lazy fuckerGuys, I got an AWESOME zombies mod that was alive a while ago. There aren't many round these days. The mod is called: reign of the undead.
Google it!
l4d2 is cool, but how many members have that, how much work would that be for wally, does wally even have the game, will that cost more, and how often would we actually use it? It is also a completely different style of game. Just because it includes zombies doesn't make it what these guys are askin for.
L4D server would have almost no problem with hacks though