Beware of Outlook 2003
I been using the add-in (.64 version) for months with Outlook XP and it works fine.
A co-worker got it for his system and has been plagued with problems because issues with Outlook 2003.
Netcentrics are not very responsive. They have a thriving community of people dedicated to using the software and making it better but Netcentrics is very non-communicative.
So my advice is use it with Outlook XP but don't expect much growth from the product as it appears these people are behaving the same way the Actioneer developers have.