Summary: I have always used APC in the past at work and at home.
However, I own lots of Belkin products and decided to try another one.
It was far less in price, smaller for more watts, is dead silent, black,
can stand or lay down easily and has lots of connections. What more
can you ask for in a battery? Yes, the internal batteries can be replaced
and there is software for Mac and PC both. Although the software was
reviewed by some as being poor, I find it great for most personal use.
(The Mac version is very simple to use and understand but there seems
to be more options for the PC.) I would strongly reccomend this to
anyone and already have, several times. I hope they come out with
larger ones for businesses and home entertainment systems as well
because I would certainly get more.

Summary: I bought this unit mainly to protect my AV components that are black. This unit looks nice under other AV components and has more outlets (8) than most UPS's. The AVR feature will come in handy during the frequent brown-outs in my area, and I may be able to enjoy the music through short black-outs. Furthermore, I won't have to set the clock again after black-outs. As a UPS for a computer, however, its performance was disappointing. I have an APC Back-UPS Pro 1100VA UPS which seems to be almost twice as heavy as this unit. I performed a run-down test and the APC UPS lasted 36 minutes while this Belkin UPS lasted only 21 minutes with the same computer/monitor setup.

Summary: It is a nice unit capable of supporting high end PC and some more. I have a PC with 1.25TB raid array and the load registers at about 30%. It is quiet, light and small.
However this comes at a price. The battery runtime at full load is listed as 2 hours(!) on the spec sheet.
However when the AC feed is disconnected, the battery goes from 100% full to 70% full instantly and then goes down 2-3% every minute. So I would estimate the runtime as 25-30 min under 30% load. Nowhere near 2 hours. At full load it should provide enough time for shutdown, nut no more thatn that. Other than runtime I am quite satisfied with this UPS