ARP Spoofing Attack

Lately i`m getting busy with this problems, ARP Spoofing Attack infected in my workplace, very hard to handled it, because i got about 40 PCs to installed and i`m too lazy to do it...LOL. Because i have done it before and it `s attack again...i hate it. I`m just thinking if i am install all computer but this attack coming again, should i do it again and overagain ... ?I`ve read from wikipedia