You can write a client for your business using VB.
There are some issues like using a custom-built client cannot be automated the same way the system login is. A user would have to start the system but you could put an entry in the Registry toforce a modal window so that the user had to login before gaining control of the system. I have not personally done this but and therefore I would be concerned about unauthorized users gaining access to a local machine's resources but I believe thenetwork resources would be as secure as if you were using the integrated client.
If you are interested, you can reach me through the peer directory for further comment or direction.