Catering Application Deployment

I have a desktop application that is partially written in C# that ties into a local MicroSoft SQLExpress database on the PC. Before I get too far along on the application, I would like to do 2 things: I would like use an XML file as a database that the application can use, rather than the SQLExpress. I want to do this, because I think that this would be better for deployment purposes. I would like some advise on this ??" should I use SQLExpress or an XML file? I need a deployment package, so I can deploy this to users via either a CD installation or through download from a web site. ## Deliverables After I get the database and deployment part of this done, I will want further work done (not part of this initial work). This will be to refine what is already there.