Oh, one piece of advice concerning testing UPS's. never ever ever plug a line tester ( a real one, not the little light test) into a UPS. Since a line tester is designed to sample how much amperage is available, it'll try and draw all the power at once. The UPS will happily oblige. The tester I was using got VERY hot in less than a second and all the magic smoke came out. Turns out it actually says in the tester manual not to ever plug it into a UPS, although 220 is fine.

Also, if you're in the US, be very careful not to buy an APC 420i or anything with an i on the end of the model number. I learned the hard way that this means International Version, I.E. 220. Nothing quite as embarassing as convincing a client to buy a UPS to protect their valuable server, getting your secretary to order one, plugging it in and all of a sudden a 4" flame shoots of the the (now dead) server. Luckily all it ate was the power supply and some dignity.