I am trying to configure a computer (yet to be purchased) to use virtual (pc
or server) and can't figure out how to plan for memory. If Vista is used as
the host and it can only use a little more than 3gb of memory and if I
understand my reading the sum of all memory for virtual machines could not
exceed the physical memory available or is that the memory available to the
host OS?

If I have a 4gb machine can a VM use the part of that 4gb that my host Vista
cannot use? What about on a 6gb machine?

I need to support Vista, XP, Server2003 and Server2008 when available. The
servers will have SQL2000, SQL2005 and SQL2008 (when available) and at times
Oracle and PostgreSQL. The machine is for application development and will
not be used in a "production" mode. It is not clear to me what is the best
choice for my host OS. It seems that if I host with Server2003 I might be
able to better utilize more memory, is that true?

I am inclined to use Virtual Server, but don't really know if that provides
any advantage over Virtual PC, any suggestions?

Thanks