APC Back-Ups Office - Doesn't protect at all

I too have never heard of cyberpower.

For the most critical applications, ONEAC, for the not so critical applications, APC (and not the cheapest line).

Actually this is exactly how a typical computer should be sized to the UPS. As MOST computers only draw approximately 1/2 the power supply rating 90% of the time, rating the UPS to backup JUST the computer (not the monitor also) is correct and standard recommendation. If an individual has not checked the typical current/wattage pull of their computer, and since very few computers draw near the full rating of the power supply, the later recommendation for typical home use still gives plenty of extra power margin.

If longer run times are required, more than the expected 15-30 minutes, then make sure the UPS will actually run longer when it is not under a larger load. Most cheaper UPSs run x-minutes regardless of the load connected.

There is no relevance to what % of the power supply is used. The relevant parameters are amperage and uptime.

Again, no. The UPS rating is a maximum. As with any supply (including the system power supply) you saw it was rated for MORE than the system used. Similarly the UPS should be rated for more than the PSU uses. "Uses", not what it's rating is in watts.

Mentioning the full rating of the power supply as a means to pick the ups is simply invalid. It may be true that some marketing departments do it merely because they know the average consumer would not be expected to know the actual current of their system. However, even these UPS tend to have more than one outlet so it still can't apply.

Wrong, they run until the lower battery shutdown kicks in or the temp rises too high (if thermally protected). Any UPS that unnecessary shuts off after X # of minutes is a bad design- though certainly their software might be set to shut the system off after a period.