I now use a 800VA Xenon Pure Sine-Wave UPS with a 160Ah battery that supports my office cabin - total cost with battery trolley was Rs 14K. It gives more than 4 hours of back-up for my PC, AIO Printer, Cordless Phone, DSL Modem & Wireless Router. I also have a similar setup at home that powers Samsung 46" LCD, HTPC, DVD Player, BriteView Media Player, Nintendo Wii, Stereo Receiver, DSL Modem & Router - never tested actual back-up time, but once saw "Bourne Ultimatum" full movie during a power cut. The one in my office is 3.5 years old and the one in my home is just over 2 years old - never faced any issues with either of them. I got the same setup for my parents also.
Cheers.