>Hi, I'm starting a small new project in VFP with SQL Server.
But this time I want to use 3-tier architecture, so that in the future I can change the presentation tier into a web page or else.

If you might want to use the data processing on other platforms in the future, push as much of it as possible to the SQL Server,
Do as much of it as possible in views, functions and stored procedures on the SQL Server.
SQL Passthrough did that well for me.
I'm using SQL code originally written to be used by VFP apps in .NET apps now.