At the office every computer has a APC 350 for basic power protection. They don't last long, but with power chute installed they will last long enough to shut down gently. At home where the budget is a little smaller I use this guy:
At one place I worked at we had very dirty power (and the power company had a bad habit of cutting off service without prior warning). We let our HP DC series PCs fend for themselves on the dirty power (except for VIPs) and they were mostly fine. However we had a fleet of about 25 to 30 Mac G5s (and later the Intel variety). Those aluminium beasties are notoriously picky about the power that they want. The slightest change in voltage would cause "unfavorable results". Thus we mandated that with every Mac desktop that was purchased an APC RS 1500 must accompany it. Yes it was expensive, but it was fun to hear a symphony of power units beep all across the office whenever the voltage changed too much.
I've worked in old building where the electrical system was, let say, less then reliable. We had workstation plugged in UPS where we experience the most frequent fluctuation simply because we did not want the personnel to loose their work if a powerdip lasted long enough to cause the computer to shutdown. We used the smallest APC UPS we could get since it only needed to last for a few seconds (5 minutes at best if we had a power outage). The one thing we had to do however is buy the cheap child power outlet protector (you can get these everywhere) to prevent staff from plugging it fans or other motor into the unit.
In other parts of the building, where the electrical system had be redone "recently". We used APC brand surge protector. Our experience was that the cheap surge protector that you can get at Walmart did not always trip when it should thus allowing the powersupply and computer component to be damaged during a surge.
I can highly recommend the APC Back-UPS ES 700. We have a few at work and I also have a couple at home. They come with 8 sockets total, with 4 being battery backed. It also comes with a socket to plug your phone line into and you can connect to it via USB, so it can detect for power failures and perform an automatic shut down. Although I must admit the software is ropey.
Every workstation, IP phone, monitor, printer, etc is protected by a consumer-grade surge protector here. In the case of mission-critical workstations, we have a mixture of APC UPS devices that provide surge protection, power cleaning, and battery backup.
This should be the case wherever electronics are used.
Yes, Brick Wall and Tripp-Lite ISOBAR are the gold standards in non-UPS power conditioning. I I use these for anything more costly than a standard IT workstation.
Even the cheap powerstrips can provide protection. I worked at a place where the 660V line crossed a lower voltage line just outside. Everything powered-on not on a cheap power strip died. Almost everything on a cheap surge protector lived (except for the power strip).
Mass market PC power supplies have high failure rates, though not quite as bad as a few years ago. Generally anything that is 80Plus certified is pretty reliable. Read http://www.JohnnyGuru.com for more details.