Nothing will run while the computer is in standby mode.
And it will not wake up out of stand by mode to run the scan either. If just
the screensaver is on or the monitor has gone to sleep, then yes it will
scan. But not while in Stand By mode.
This is a generic response to most background running applications. Correct
me if I am wrong about MS AntiSpyware, though I doubt MS AS 1.0 Beta is any
different in this regard.