I've always had good luck with APC UPS systems. I'm sure that they could spec something out for you using their UPS selection system, although I find that they often over spec for my use. I've used everything from the low end office units to the big server power setups and I've always been pleased. I also used Tripp Lite and CyberPower, mostly because of price- I got great deals on them and they're fine for use in my apartment where the power rarely goes out and where minor line conditioning problems are more of the normal problem.
At the very least, you need something that can handle the surges and fluctuations, and if you have several computers, you might want to get one of the heavier units that really can handle some nasty stuff.
Z.