Running Outlook 2000 with Exchange 2003

A year ago I manually archived all my "old" emails - and wrote up
instructions so I'd know how to do it this year. This year, it's not
working.

I move my old items to a new folder, go to File | Archive, select the
folder, tell it to archive items older than today (I've checked and
the items to be archived all have Modified Dates older than today),
check the box to include things marked "do not archive", make sure
the .pst file referenced is the correct one, and tell it OK.

Outlook tells me it's archiving, and when I look at the file size of
my PST file (in Windows Explorer) it has gotten larger, but my OST
file does not get smaller, the emails are not moved from the original
folder, and they do not show up in the archived folder.

Just to be sure, I tested the entire procedure on another machine in
my office, one where no archiving had been previously done - went
through the whole archive procedure, then went through Tools |
Services | Add | Personal Folders to add/open the archive PST. The
archive folder shows up properly in the Folder List, but nothing is in
it (and the items are not moving from their original folders).

Am I doing something quite wrong? Did an OS patch sometime this year
break something pertaining to archiving? (I know Outlook 2000 is
quite old, but still ...)