Actually, SQL Server does not have to be slower than dbf tables. Hardware is cheap. On a dual pentium server with 128M RAM, SQL Server does just fine.
I don't see what the fuss is. Use local tables for lookup tables and non-sensitive data. Use either dbf files or SQL Server/Oracle/whatever if there are security, size or network issues. As long as you use parameterised views, it doesn't matter a jot to development.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
