Keep in mind that the closer the power draw is to the rated power draw of a UPS, the more efficiently it runs, which is somewhat counter-intuitive. Tripplite has nice graphs of this on their website. So getting a 900w UPS when your typical power draw is going to be closer to 150w is going to make it run inefficiently, which means energy is wasted as heat.
I think a high end double conversion UPS would always see this inefficiency, but cheap UPSs will not, only when they are on the battery (which is when it is important for battery duration). Anyways you might want to look closer to the 300-500w range depending on how many peripherals you are running.
I have a new 27" i7 iMac, a 2 channel class A/B amplifier, a voip phone, PoE switch and router all running and my typical power draw is about 180w via a Kill-a-watt. Running Portal full blast for a while and I could only get it up to 310w. I'm running on a Tripplite OMNISMART500 which is rated at 300w/500va (power factor of .6, just like the APC & Cyber), and it works like a champ, it's silent, doesn't give off too much heat, has a user changeable battery (the real cheap UPS's do not), and has HID USB so the USB works just fine with OS X.
There's a guy selling the OMNISMART500 on eBay brand new for $57 shipped,
they are quality UPSs, very basic but well made, they sell for closer to $150 normally.
The LCD feature is gimmicky, on the low end UPSs I've seen they only show you volts which is pretty useless, watts or amps would be far more useful. Get a kill-a-watt for $20 and you'll get far more useful information and you can use it all around the house. After the first 5 minutes of having your UPS, you'll never look at that LCD panel again
I think Cyber Powers "Adaptive Sine Wave" is a more marketing crap, the power factor on that UPS is lower than on the APC or the Tripplite, although pretty close (.58 vs .6). Higher quality UPSs like the Tripplite SmartOnline series or the higher end APC Smart-UPS will have a power factor closer to .8.
If you get a single battery UPS it will cost half as much to replace the battery in a few years as a double battery UPS. Most small UPSs use the same batteries, which are 12v 7-8 amp/hour, 5.94" x 2.56" x 3.74", very common form factor, they are used in emergency lights, and are relatively inexpensive. But some, like that APC, have plastic moldings on them, which is probably just to encourage users to purchase their replacement from APC for inflated prices when the time comes. That is something you may want to consider. You can get an off the shelf Powersonic PSH-1280 for $20, which is a very high quality battery, probably better than what the UPS companies OEM.
Personally I use Tripplite ISOBAR's for surge protectors on all my electronic gear that I care about, they are very well made and protect up to 3800 joules.
Don't splurge on a UPS, you just need it to work for 5 minutes to get you past short outages, or let your computer run long enough to shut down for a long outage. Get something well made but don't go overboard on capacity. If you splurge, I'd splurge on quality, not capacity.
regards,
Rob