One word of warning. A number of UPSes will not re-power after you have shut them down when the power is out.

In other words, the power goes out, the UPS kicks on, everything is good, you decide to shut down your laptop, but then later when the power is still out you want to turn the UPS and everything back on and... The UPS will refuse to turn on.

Also, make sure the alarm can be silenced. :-)

-john