A:
You should put an APC on every single piece of equipment you don't wish to be damaged by lightning or have service loss. Computers, NAS Arrays, cable box, game console, network routers/switches, any electronicly-powered musical instrument, televisions. Absolutely everything that has value to you. Not only will this condition the power so you have more reliable operation from these devices, but when that lightning strike occurs, or the power-outtage occurs, you have no disruption for at least enough time to shut things down safely, or ride through short-term outtages.
An uninterruptable power supply is the most cost-effective day-to-day insurance you can have because not only can it save you from inconvenience, it can also save you from catastrophe. Sure, home-owners insurance will replace things-- but in the meantime, you're down and out, whereas with a UPC, your outside cost is the cost of the UPC itself.