Not sure how you read the n/g, I use Outlook Express and have the n/g set to
display unthreaded messages in chronological sequence. When I want to search
a thread, I select a message in the thread and pick the Subject header,
which then alphabetizes based on the selected message - meaning I see the
whole thread. When I want to see all messages sent by some person, I select
one from them and then click on the From header which alphabetizes as above,
so all of that person's messages are right there. Same with Sent (which is
how I normally browse).
I realize that this isn't exactly an answer to your question but maybe it
will help?