Outlook Plug-in versions

Outlook Plug-in versions

Hello,
 
Could not find this answer elsewhere.  We are very interested in this Plug in , but we have some users using Outlook 2003 and some using Outlook 2010.  Do all user need to be on the same version?  If no, then are there any functionality differences we can expect between the differnces? 
 
Thanks for your help.