I don't mind too much wether they're fast or slow, so long as it's explained well.  'Rager' (fcast) zombies in 28 Days Later were well explained, because they weren't actual zombies (as in corpses risen from the dead); they were individuals infected with something akin to rabies ('rage virus').<br/><br/>Having said that, though, I DO prefer the classic Romero Zombie.  Despite their slow, plodding, jerky movements, they're still an amazing threat.