Hey Paul.

Identifying the user of your forms is often essential and usually very
handy. I do this on nearly every form I create.

With 2007 they have a username function. Also there is code you can run
which get the current user.  The only downside of this is that code requires
a full trust (installed) form and that in a VPN / RAS / Remote situation the
local  user name is not typically what you want.  You wan their domain
credentials.

If you have SharePoint there are some ways to use a web service with 2007 or
some work around in 2003.

I use an Active Directory web service. Not only can I identify the domain
credentials of the user each time they open the form but I can also query
Active Directory for their email, address, location, department, address,
etc.  I can also use the web service to look up other users information or
check group membership.

An example is available at http://www.qdabra.com/proddetail.asp?prod=QADWS