I have had no trouble with this combination, the only thing to watch out for is the security settings in the NT based OS'es that can catch you out.
From memory Groupwise uses VIM? the integrations not great but works pretty well.
For the best Email integration you really want Outlook 2000 or XP running in the Corporate and Workgroup mode this will give you the full extended MAPI integration.
Regards
CABC Support