See inline...

>So the issues are
>1. Deployment

MSDE installation can be installed as part of the VB application setup. There is an article at support.microsoft.com that says how.

>2. Scalability

You can change from MSDE to SQL 7 only by changing the connection string.

>There are about 20 Users.

Oups.

>I'm used to SQl Server 6.5. When I installed MSDE I don't see any interface or anything, just a screen where i can start the server.
>
>1. I don't see where I can manage a database; be it creating one or otherwise.

You need Enterprise Manager or Access 2000.