Hi
The best option I tested was Cryptor from xitech
http://www.xitech-europe.co.uk/Other options are database events in vfp 7, and file protection from windows nt, 2k, etc.
Database events aren't bulletproof, and file or directory protection need n-tier programming with com components.
Cryptor encrypt database with a few lines of code, and you can use it without modify your existing code.
HTH.