All:

Env: Windows XP SP2, VS 2005, VS for Office (most recent), Outlook
2007

I would like to implement an add-in that works in both OL 2003 and
2007. Is this possible, or do I need to build a version for 2003 and a
version for 2007?

(Assume that I am not using anything specific to 2007, e.g., the
ribbon).

Thanks,
John