Have you taken everything apart and put it back together again?mainly reseat the CPU.... and try a bios recovery update and a CMOS clear
I've run into the exactly same issue with the same motherboard and processor. The motherboard sees only 2 cores instead of 4. I have the latest bios and I tried reset the settings. No change...
I've installed Windows 2008 and it sees the 4 core in the device manager but why show only 2 cores in the BIOS and the hardware info of the Vmware Server?
I would like to give you just a quick info that the Intel® Desktop Boards do not currently support Microsoft Windows Server 2003 or 2008. Please make sure that you are using a right operation system on your computer. More info please visit: http://www.intel.com/support/motherboards/desktop/sb/CS-008326.htm