Hello ,
Thanks for the help , but it appears that the gang of three ( Microsoft with HYPER-V, VMWARE with ESXi 5.0 , Citrix with XENSERVER ) had 
something like an "agreement" . I'm joking . To implement hose  3 features  or to virtualize them  , one needs  VTD IO features enabled on the BIOS.
For the particular case of VMWARE ESX , it's a very peculiar  product and one has to read very well the compatibility  list it releases for each product.
If you don't tread their line , your setup just get stopped and there is no way to work around.( By the way : ESXi3.5  requires also VTD for Intel Chipset  or AMD-V for AMD chipset in addition to the aforementionned  ICH7 + Network adapter  )
For VMWARE ESX  , its a best practice to have at least 2 ethernet  adapter card for High availability. Any non recognised card is just ignored and appears nowhere in your environment . 
It took me two months to find out a mobo that met the requiremnts for VMWARE ESXi3.5. It still works for ESXi4.1 but nomore for ESXi5.0.
( see reason  erstwhile ).
Hope that would help someone and cheers