I'm planning a new ASP.NET project that will become a product that is installed by techinical staff that work in various companies. The program will be storing sensitive information that shouldn't be easily accessible to staff including the technical staff.

I need to balance an easy straight forward installation with security and reliability. The default db these days seems to be MS SQL for C# developers but some companies that will be installing this may not have their own SQL server so someone has suggested I use Microsoft JET database. What is MS JET is it a product or a technology? The database will be quite basic just a couple of tables, I don't need all the power of SQL, are there any db suitable that don't require an installation like SQL (i.e. a simple file)?

Thanks J