Open Source Embedded Database Options for .Net Applications

I have a .Net 4.0 WPF application that requires an embedded database.

MS Access doesn't work on 64 bit Windows I'm told. And I'm having issues with SSCE:

Unable to load DLL 'sqlceme35.dll': This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix this problem. (Exception from HRESULT: 0x800736B1)

sqlceme35.dll is installed into my application's program files directory, so I can't seem to figure out why Windows XP Pro doesn't see it.

I was wondering about other embedded database options I might use (that work on both 32 and 64 bit windows). Any suggestions?

SQLite

...and the System.Data.SQLite provider.