M$ on Windows 8: Developers, Bend Over and Take It.........

[Mumps]

One caveat I forgot to mention. If you wish to create a 64bit "Guest" then the Host OS must be 64bit. But you can run 32bit Guests on a 64bit Host.

Actually, in the documentation, VBox indicates you can run 64 bit Guests even on 32 bit O/S hosts. As long as the hardware supports it...

3.1.2 64-bit guests
VirtualBox supports 64-bit guest operating systems, even on 32-bit host operating systems,2 provided
that the following conditions are met:
1. You need a 64-bit processor with hardware virtualization support (see chapter 10.3, Hardware
vs. software virtualization, page 157).
1See chapter 14, Known limitations, page 181.
264-bit guest support was added with VirtualBox 2.0; support for 64-bit guests on 32-bit hosts was added with
VirtualBox 2.1.
40
3 Configuring virtual machines
2. You must enable hardware virtualization for the particular VM for which you want 64-bit
support; software virtualization is not supported for 64-bit VMs.
3. If you want to use 64-bit guest support on a 32-bit host operating system, you must also
select a 64-bit operating system for the particular VM. Since supporting 64 bits on 32-
bit hosts incurs additional overhead, VirtualBox only enables this support upon explicit
request.
On 64-bit hosts (which typically come with hardware virtualization support), 64-bit guest
operating systems are always supported regardless of settings, so you can simply install a
64-bit operating system in the guest.
Warning: On any host, you should enable the I/O APIC for virtual machines that
you intend to use in 64-bit mode. This is especially true for 64-bit Windows VMs.
See chapter 3.3.2, “Advanced” tab, page 42. In addition, for 64-bit Windows guests,
you should make sure that the VM uses the Intel networking device, since there is
no 64-bit driver support for the AMD PCNet card; see chapter 6.1, Virtual networking
hardware, page 83.