I am not sure whether the board DG45FC does support Virtualisation. I am sure that all the AMT Intel board like dq965gf, dq35jo, dq45ek,dq45cb (All 'Q' chipsets boards) support virtualisation.
Now the main thing -
From the Technical Specifications Document for both boards:
TPS for DQ45CB: http://download.intel.com/support/motherboards/desktop/dq45cb/sb/e42785001us.pdf
TPS for DG45FC: http://downloadmirror.intel.com/15992/eng/DG45FC_TechProdSpec.pdf
I can see that only in the TPS for the board DQ45CB, it mentions something on Intel Virtualisation. Page 32
I have checked in the Specification Update, Release Notes for Bios.
Probably, the board DG45FC does not support Intel Virtualisation in the bios. Usually, the Intel VT is found in the BIOS >>
I am 100% sure that the board DQ45CB and other AMT boards have this option in the BIOS.
I have attached a screenshot of the bios for DQ45CB - where it shows that Intel VT is available for this board.
Hope this helps you a bit.
Virtualisation on DQ45CB.doc 31.0 K