My MB numbers are from the Add or Remove Programs list. The custom installation of v6 below comes to only 137 MB (vs 195 MB for the typical install).
As some others have suggested, and after some meditation and sleep, I decided to try a custom install of v6, omitting the WebCal thingie, the Mail Shield, the Scripts Shield, and then disabling the sandbox thingie. I don't need the Mail Shield because all of my email gets bounced through google (gmail) and they catch all of the bad stuff. The Scripts Shield is the probable cause of my Outlook Express opening script problem, although that isn't proven absolutely hereby. And I don't want any sandboxes nor the WebCal to interfere with proper operation of my computer.
Result: the script error when opening Outlook Express is gone.
I also note that avast5.ini remains even in v6 (why didn't they rename it avast6.ini?) so I can enter the further custom modifications I want thereby.
This makes v6 acceptable to me...