I finally heeded Microsoft's warnings and installed Outlook 2003 after
resisting for so long ("resistance is futile"), and uninstalled Outlook
Express after being satisfied everything was migrated over and functioning.

Previously, during my time with Express, something (Norton, I think)
triggered the Identity Login dialog to pop up in the beginning of any
session, Express running or not. This is a known problem with Norton and
I've learned to live with it all this time. After performing the switch from
Express to 2003 and uninstalling Express, I figured it would go away, being a
part of Express, but lo and behold, the same dialog still pops up asking for
a profile (I assume because of the same Norton Liveupdate issue).

How do I get rid of it?

Jon