Database solution needed for client side Silverlight app.

Question

Here is my situtation:

I have a Silverlight application that was written in C# which needs to load some data from a database (or XML if possible). We currently use SQL Server to store this data in house, however, when deploying to a client we cannot use SQL Server or demand that the client install and configure SQL Server on their web server just so the Silverlight application can use it. Are there any deployable, small, database solutions available similar to Access's .mdb files that we can deploy with the .msi package so the client will have a small database solution they can use without all of the overhead of installing SQL Server?

I was thinking about using an XML document, storing the data in there on the server and then when the Silverlight application loads, loading the XML as a stream from the server into the application and from the stream into a DataSet object but I am not sure what the size limitations are when attempting to store data in an XML format. Thanks for the help :)