I am trying to Impersonate a user in a .NET Windows Application running in
Windows 2000 SP4.  Whenever I try to do the impersonation, I get an
exception which states "A required privilege is not held by the client."

The user that the application is running under has the following access
rights "Create global objects" and "Impersonate a client after
authentication".

For some reason, the only way I can get the impersonation to work is to
assign the user to "Act as part of operating system".  I would prefer to not
do this.  Is there some other access right that the user must have in order
for the Impersonation to work properly?

For the impersonation, I am using a WindowsIdentity object that was
constructed from a Windows User using the LogonUser Win32 API handle that I
obtained through my own .net wrapper class.