In follow up to this I still have a problem unfortunately!
Whereas a User with Office 2003 Professional loaded has 'Other User Mailbox' in the File, Open box and can successfully access a Shared Contacts folder I set up, but I have 'Other Users Folder' in my File menu. This is still greyed out after installing SP1 and then SP2 to my Office 2003 Small Business Edition installation.
I realise this probably has nothing to do with Zimbra but would appreciate any help.
Any ideas Guys?