SQL Server CE is a good choice for storing and organizing your data, but it is not the only choice. There are two lighter-weight alternatives you can use:
You can create your own DataSet and use its built-in capability to persist itself as an XML file.
You can use a custom object and use XML serialization to save its state to a file.
Persisting to a file is often used for simple data records such as the settings for an application.
You can add a DataSet to your project and use the Data Designer to design tables in it, or you can create a DataSet programmatically. Then you store your data in it in the same way you do using a DataSet that you created by dragging tables from a SQL Server CE ...