C# + XML as Database

Question

Hi Everyone, This is my first post hope I chose the right section ?!? I am planning an application to deal with patient details & visits. Due to a little number of patients msx 300-500...instead of Access or any other database, I decided to go for XML backed database (its free + I heard its possible to use xml as a relational database). Apart from the fact that I want to take it up as a challenge.(no deadlines hehe) Obviously if you think its not worth it or not feasible please let me know. Maybe after all XML as database is not the best way out. The tables setup is simple 2 tables (Patient---(one-to-many)---PatientVisits). I might add a ComplexType (in Patient) to deal with accounts but not sure yet. Now to my question anyone know of any guides or even sample win apps preferably VS.2005 solutions.I'm used to the old VS.2003 XML designer but am confused in the new 2005 one. Also helpful would be guides on how to set the XML (Schemas, Relationships, Constraints & Cascading, XSLT??) and maybe some Security?? Sorry for the long post but I can't explain it in lesser words. I'd appreciate any links or help Thanks Lukas