Advice Please: Fedora 9, Amd Phenom 9600, Nvidia GeForce 8400 & Virtualization.

[Nat Gross]

My boss "loaned" (ahem, my job is to get Linux on it)  me a new HP Amd
Phenom 9600 system with a GeForce 8400 video card, with Vista64 sp1
installed.
I want to put Fedora 9 on it (and hopefully it will be the main os it boots).
A key requirement is to run Linux & Vista simultaneously
(virtualization), plus if possible multiple Fedora 9 vm's.
Running Solaris as a guest vm is in the 'it would be nice' category.
My question is: Which virtualization technology do I use?
Also, can I tell the KVM (or Xen or whatever) installer to run the
Vista guest machine off the existing boot partition? (so that if and
when we boot into Windows we should be using the same Windows as when
it runs as a guest under Fedora 9.)

Thanks in advance.
nat
ps. system has 6 gig of ram.