APC is generally recommended as the best. I've got one of them, a little 250VA thing, if I remember right, which powers my network stuff - a router, a switch, and a cable modem. It lacks a mute button for the speaker that beeps when the thing's on battery power. A soldering iron fixed that though - the little piezo speaker now goes by the name "spare part." 🙂
My systems user Cyberpower UPSes from Newegg. Low priced for the capacity, but they come with a functional utility that lets you monitor voltage, load, temperature, and frequency. It also lets you set the voltages that trigger the backup power source - both if it's too high and too low. It also has automatic voltage regulation (1100AVR and 1250AVR are what I've got), which is supposed to stabilize line voltage without battery power. I'm pretty happy with these units, and they've not given me any problems. The 1250AVR does beep at me sometimes (probably from momentary overload) when I degauss my monitor, but that's because it's a good quality 21" screen. BIG degauss coil, and the cycle takes 8 seconds to finish.
My dad's PC also has a Cyberpower UPS - 800VA thing. No problems from it either.
