UPS are generally used to provide short-term power (giving you enough time to save and switch off) and protection against voltage spikes. Some UPS are smart devices and can be set to automatically and correctly shutdown/hibernate/sleep your pc, when there is an input failure, thus preventing damage to your equipment, inverters cannot do this . As mentioned, both UPS and Inverter needs a correctly seized battery bank depending on how long you want to keep the device/s running. UPS and Inverters almost work in the same way, both make use battery's and both need a way of keeping the batteries charged and both need to convert DC to AC. For the PCs at work you would need to work out the total power (watts) needed per PC and either size you UPS or Inverter for each individual PC or find a big enough unit to handle all the PC's together. Maybe using a generator would be more practical/cheaper, I'm not sure on the various prices