Deploying Sql Server with an application

I need to deploy SQL server 2008 express with my application. I would like to run the installer in an automated way. I also need to detect if the user already has 2008 express installed.

I could just be lame and ask the user directly in a custom action, but my program deals with research data and most likely the people installing would hit the wrong button and overwrite their database or something.

Any ideas? thanks.

These are 2 different things: SQL server 2008 express and the database containing your data.
If you create a setup project it will al go automaticly.

There are some notes on this at Distributing SQL Server Express.