Yes, the APC's are good, but some APC's are better than others - particularly the software that comes with them.
Basically, you'll want to plug anything that is important to stay alive during a power failure. Don't plug a printer in though, particularly a laser printer, as they have large startup surges that can kill your UPS. Most likely, you'd want your computer, monitor, and maybe cable modem/etc. if internet access is important during a power fail.
Most of the mid-level and higher UPS's will have one or more battery backed-up outlets, and one or more surge protected outlets. You can use the surge protected outlets to protect other components such as your printer, but no power is provided when the power fails.
The batteries should last at least a couple of years. I had a cheap UPS die after about 2 years, I've had others that are going on 3+ years now. If you overload it, the batteries will die sooner.
As far as which is best....tough question. A lot may depend on whatever goes on sale next. I just picked up an APC 500 a few months ago for about $20 AR at Staples, and it's very nice. Good software (i.e. allows me to turn the beeping off); I'm using it on my TV/Satellite right now. The batteries can be changed - you'll have to search online or eBay for them - but the whole units go on sale regularly for $15-$25 AR which is the route I go.
BTW, I like the mid-level Belkins as well. The software seems nicer than some of the APCs have.
