Techspec's shows that the cpu has vt-x
So it should support it.
Snoop around in your bios to see if there is not a other option hidden somewhere.
These HP biosses are a crime to understand sometimes.
Also i would take a look @ this :http://communities.vmware.com/message/705601
if its still not working i would contact hp about this.
Thanks for that.
Yes I looked everywhere in BIOS, but found no more hidden Options - its a fairly new (compared with the age of the xw6400!) BIOS ( 12/2010 ) and has a VT Enable so I expected it to work.....
But I think I may have stumbled on the answer, which I record below in case anyone else hits the problem....
I should have given more info in the original mail - the workstation/server is running W2008 AND HYPER-V - I believe this combination disrupst both the Intel Processor ID utility and the 'old' VMware 64 bit Compatability check, because they were both working under an o/s that has virtualisation already enabled....
So once I found the vmware cpu identification utility at http://www.vmware.com/uk/support/shared_utilities.html which is an iso and does not run under Windows etc. - it gave the correct answers.
Moral of the story - don't try and mix your virtrualisations.
Hope that helps.