rr style scanning of non-customers

but where is the equivalent for windoze, the very common and very
vulnerable opsys?

IMHO, the best place for windoze folks to start is here
This tool detects and removes a whole pile of nasty intrusive software
that virus scanners do not pick up. And Spybot S+D also has an immunize
function that can block future intrusions.

Of course, they could also buy and install some commercial windoze
firewall software but the cost of this is a barrier for a lot of folks
unless they have seen it in action on a friend's machine.

Beyond this, http://www.apple.com is a good place to find solutions to
this problem.

--Michael Dillon