I just finished installing a brand new UPS system for my desktop. I used American Advanced Power's APTX-350 a powerful and innovative UPS that replaces the power supply and locates the battery unit internally in the chassis. It is incredible because the whole unit is invisible, the power supply looks like a standard unit and the back-up unit is located in my 5.25 drive bay. I get 50 minutes of back-up time and it all fits neatly in my chassis. It is kind of spookey the way you can have it powered on with out any cords running to a wall socket. They have all kinds of models that serve different purposes and power needs. I got it from there website which is www.ups2.com.