You need to install the post-SP4 hotfixes for Exchange and if you access the
same mailbox using Outlook 2000 and 2003 you might have problems because
there's an extra free/busy field that can prevent Outlook 2000 from closing.
The fix is to start Outlook 2000 with the /cleanfreebusy switch. Although I
haven't noticed that problem lately since Outlook 2003 SP1 when I access the
same mailbox from both versions of Outlook.
Other than that it works fine. I use that combination here.

Signature
Ken Slovak
[MVP - Outlook]
http://www.slovaktech.com
Author: Absolute Beginner's Guide to Microsoft Office Outlook 2003
Reminder Manager, Extended Reminders, Attachment Options
http://www.slovaktech.com/products.htm
> The official word from Microsoft is that Exchange 5.5 and
> Outlook 2003 are compatible:
[quoted text clipped - 4 lines]
> However, does anyone know of any specific communication
> issues involving that combination?