Using Access 2003 ADE with SQL Server (various flavors)

Our Access ADE is locked down, so that users have to enter via the usual
username/password route.
No-one can see the project window (database tables, queries, etc) and all
updating is done through forms.

BUT

If a user loads up Excel, he can go Data - Import External Data - Import
Data, whereupon all our backend tables, etc pop alarmingly into view!!!
Aaaaargh

Other developers must have come across this 'feature', so if you have any
suggestions as to plugging the leak I would be very pleased to hear them.

The only idea so far is to remove the Get External Data option from Excel

TIA

Steve