Ways to stop access to a SQL express database I have a SQL express database and was wondering what options I have for securing it?

More specifically it is a replicated database using merge replication. I want to stop a user with a replicated copy of the database opening the database, modifying it and running queries against it.

UPDATE:

Just wondering though, what happens if I have a database which is secured, but I then take it offline, copy the database, and attach it to a different database server. Does the security go with it, and can I not break into it like that?
There is no way you can secure a SQL Express database against access from a computer administrator. In the typical SQL Express scenario this means that the user of your application (which is usually a also local administrator) can see everything in the database and it can also modify anything, no matter what grants or permissions you establish. 

If you want to protect the IP in the database (which is the usual reasoning behind this ever repeating question) you need to prevent access to the physical database which you can only do by no releasing the database to start with. In other words, use a web service instead (hosted by you), or a cloud based database like SQL Azure.