homegroups between VMs and Host

[MacNala]

I am having difficulty understanding what is required to set up a homegroup which includes all my VMs and the Host machine.
I have all my VMs and the host using a Public workgroup which works (after a fashion) but now that all my VMs run Win7 want to switch over to a homegroup.
Every time I try to set it up Windows complains that I have two network adapters, the NAT one and Host Only one.
Is there a guide to doing this in Vbox?
I have set it up between my three LAN connected Win7 machines but when I try to connect to the homegroup from the VMs I get the message.
Because of this I have had to revert to my Public workgroup method.

Main machine Win7 Ultimate all others Win7 Professional. All 64 bit.

[Perryg]

I think that you will need to use bridged mode before Windows will let you use home group.