To add users go to [ System / Administration / Users and Groups ], or
in Unity [ Dash / Users ].

To manage groups go to [ System / Administration / Users and Groups ]
but in Unity it looks like it's command line only. Notice you've got
the classic shell running in 11.10 so do the paths above work ?

If you are getting the 'Install Guest Additions' message when trying
to use Shared Folders then go to [ Devices / Install Guest Additions ]
and see if that helps. Not sure if it's a VBox us 11.10 quirk so
having a bash at installing it in 11.10 running in VBox - will be an
interesting exercise if nothing else

Well VBox 4.1 is installed, added user to vboxusers, installed WinXP
fine and after going to [ Devices / Install Guest Additions ] access to
shared folders was there - no need to install VBox extras in fact.

Personally I'm looking forward to 12.04LTS and hope that the lack of
usability in Unity for advances users is dealt with. Agree it's too
simplified for the serious user, but fine for the casual one. In the
meantime, using 10.04LTS for all my daily computer work.

PS - does installing WinXP in Virtual Box that is installed in Ubuntu
11.10 running in Virtual Box that's installed in Ubuntu 10.04LTS count
as 'serious geek'