The ones that say they include voltage regulation, like the APC Pro series, have the line conditioner built in. These are the units that protect against brownouts and undervoltages that are damaging over time to your electrical equipment. Basic UPS's and surge protectors kick in when the power spikes, or goes out entirely, which is of course useful. But trying to run equipment at full steam when the electricity supplied isn't enough to cut it will only burn out solder joints and other electrical connections. If you don't have one, get it. Same goes for home theater. There are line conditioners for your equipment there too. Buy it, be thankful that you have protection. One less thing to worry about. And if the protection fails -- Warranty.