>Does anyone know the difference between VFP 5.0 and 5.0a?? And where can I purchase the VFP 5.0a

A lot of bug are fixed in 5.0a, the integration with Visual Studio and improvements of speed with Visual SourceSafe.

You can purchase it at the address --> http://www.microsoft.com/vfoxpro/
They give all the information to how to purchase Visual FoxPro 5.0a