I have the tower version of this line conditioner and use it with the computer system I use for my business. I can't say for sure if it has prevented any damage, but it is definitely working hard. Its status lights indicate incoming voltage, and you can hear it click when it makes a correction. Both lights and sound indicate frequent activity. In fact, based on this observation, my electrician feels that I probably need a new service into my home (all internal wiring was replaced several years ago, and so was the drop from the street, so that leaves just the service as a possible culprit).
Surge protectors can't correct voltage variations like this (only massive surges), but my understanding is that over time they can be quite damaging. I don't think I'd go to this length for entertainment equipment which can be easily replaced, but it seems very appropriate for the computer. I consider it another form of data protection (though of course no substitute for careful system maintenance and frequent backups).
