Outlook 2003 integration

I want to extend Outlook 2003 with custom functionality for contacts 
(basically, storing additional information for a contact). I don't want to use 
Outlook Forms unless I have to, as I don't like the data storage system, and I 
don't think it will easily handle what I need. The other option appears to be 
an ActiveX web control. Is there any way I use .NET in Outlook? I really dread 
the idea of going back to VB6 to develop a new application....

Thanks,
Erick