A decision to buy a UPS is at least partly dependent on the quality of electrical transmission in your neighborhood. If your neighborhood has a history of very [B]infrequent[/B] brownouts, blackouts, power surges and fluctuations–in other words, relatively stable, clean electrical transmission then a UPS is perhaps not absolutely necessary(but still a good idea.)
Choosing a good UPS requires a bit of research as well. The cheapest ones tend to provide only [B]backup[/B] power in event of a brownout or blackout.
The best type for home or small office use in a neighborhood with poor electrical transmission history would be a [B]dual-conversion[/B] (double-conversion) type, but these are still relatively expensive (at least where I live.)
If you decide to buy a UPS, do a bit of googling into each model’s specs before choosing a specific unit.