There are plenty of fine personal password managers out there, and there's no particular reason to use this. I like learning from challenges like this, and use it to prove out various techniques and as a reason to keep improving other my libraries, in particular WinForms.Library and Postulate for SQL Server Compact Edition.
This is an overhaul of a previous effort CredManagerWinForms that I've stopped working on. This version brings several UI and data access improvements. The encryption is still the same, using SQL Server Compact Edition's native encryption.