Hello
There are many ways to redistribute your application. The easiest one is called XCOPY deployment.
In a nutshell what your need to do is simply copy the program files and the database mdf file to the destination PC and use a special connection string.
Something that looks like this:
string conStr = "Data Source=.\SQLExpress; Initial Catalog=; Integrated Security=true; AttachDBFileName=" + Application.StartupPath + "\MyDb.mdf "
It makes thing easier to make store the sqlserver mdf file in a folder within your application folder.
More details on msdn:
http://msdn.microsoft.com/en-us/library/ms165716(v=SQL.100).aspx[
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Valery.