I am running Outlook Express under WinXP Pro. My mail comes in to a
Novell
GroupWise 5.5 Server and I access the mail via IMAP4. I'm looking for
an Anti-Spam program for this environment - either the XP WorkStation
or the Novell FileServer v5.0.

Try a free mozilla client for mails with some filters for spam.
another way is to create in outlook some filters, just click the
message menu and create filter or something like this