I just updated to sp1 a few minutes ago. I too have an APC UPS connected
via USB cable. The update package was offered to me and installed with nary
a problem.
I did use the update package; not the full package.
I quote from the following article -
http://technet2.microsoft.com/Windo...1414-4d11-97de-0748abdcec651033.mspx?mfr=true
"Disconnect any serial cables connected to UPS devices. If you have an
uninterruptible power supply (UPS) connected to your destination computer by
a serial cable, remove that connection before running Setup. Setup detects
devices that are connected to serial ports, and UPS devices can cause
problems with the detection process. You can leave your computer connected
to a UPS for power as long as the UPS itself is plugged in. However, you
should make sure that you have enough power for the entire installation,
which can take a long time."
The key word is 'serial' as the older APC devices used to use.
I re-iterate. There is nothing mentioned with respect to UPS and USB.