Hi c_edge
Firstly, I agree with you about memory usage being "standard" (I prefer 'typical') for XP OS AV/AS apps. That was not my point.
However,
"Majority of programs that are exited from the system tray are completely shutdown."
This is true
except for all the other AV programs I currently use! e.g.
CA EZAntivirus 7 / VET (and going back, InoculateIT PE)
AVG 7.5 Pro (6 & 7 also)
Avast 4.7
For all of these (and there may be others as well) closing or not loading the tray icon does not stop on-access file scanning.
Examples of accidental and/or deliberate exiting of AV?
When my teenage son and his friends start playing any CPU/graphic intensive PC game, the first thing they do is close all the "unnecessary" tray icons to free as much RAM/CPU cycles as possible. Leaving aside the issue of whether this is really helpful, many of them are using AVG Free or Avast Home, so they now 'know" that closing the tray icon of an AV program is okay because it doesn't stop the on-access scanning.
Many of my family and work colleagues are not very accurate "mousers". Not only that but sometimes they right-click when they should left-click....and they don't pay attention to little pop-up dialogs. I'm frequently asked why the Start Menu has suddenly jumped to the side of their screen, or why the icon for 'ISYS Search' or some other package has "disappeared" from the system tray.
Pete