Multi-boot dual-boot magic machine.

[Zaphod Beeblebrox]

So my end goal is this: that I can run win7 with an FreeBSD guest and I can
run FreeBSD with a win7 guest. and that both of these are achieved such
that there is one copy of each operating system on the workstation.

Now... I have achieved the former --- that is FreeBSD boots both by itself
and under vmware hosted by win7.  On the bare metal, this uses the nvidia
binary driver, but on the VM, it would be convenient if this used the
vmware driver.  Not _just_ that, but the nvidia binary driver has several
options to drive two monitors where as the vmware instance would only have
one.

Has anyone given any thought to

1. Detectiing system changes in loader
2. Setting system environment variables from loader
3. Having filesystem alternatives based on environment variables (a-la
DG-UX0

... or some other way to achieve this?