Sheila Skolnick thought she had plenty of protection. Surge protection, that is. The owner of Elite Companies, an $18-million hotel-supplies company in Setauket, N.Y., had been using computers to track sales and inventory for years, and, she says, "We thought we had taken all the precautions." The company used a standard-strength uninterrupted power supply and surge-protection strips.

But none of that saved her from the lightning bolt that zapped her company's computers at 3 a.m. one Sunday. The lightning wiped out the network cards in 7 of her 11 computers and taught her to set up her network differently.

Skolnick's network had been wired together in series, with the server at one end. As a result--like a string of Christmas tree lights when one is burned out--even the unharmed computers wouldn't work. Now her server is flanked by six computers on one side and five on the other. That way, if lightning strikes twice, it will have a shorter distance to travel before going to ground. At worst, it will wipe out only six computers.