Well, If I were you, I'd consider MSDE instead of VFP fpr the backend because it offers more security even though VFP database, starting from Ver. 7.0, can be made more secure when you program its DBC events than when you don't and it's supposed to be 100% compatible with MS SQL and is recommended by MS for low end web applications.

For VFP backend, you can choose the upsize wizard to upsize to MS SQL.