FYI,

VFP5 works great in NT 3.51, NT 4, and 9x
VFP6 will not work in NT 3.51, it requires NT 4 or 9x

Microsoft dropped support for NT 3.51 in VFP 6, according to
the help line, the only notice was on the side of the VFP 6 box, which
states requires NT 4 or 9x.

I'm assuming they will drop support for 9x in the next release of VFP, since
they are pushing upgrades intensively these days..