Counts logically, not physically!
by Shijaz Abdulla on 20.04.2007 at 08:37
So how do I determine how many physical processors are there under the hood? Well.. as of now, you can’t! Unless you’re running Windows Vista.
Microsoft released KB article 932370 on April 16, 2007 which basically states that Windows XP and Windows Server 2003 can’t determine the physical number of processors as of now. They are currently researching on this issue and will post further information as it becomes available.