http://www.anandtech.com/cpuchipsets...spx?i=2397&p=2
Pentium D
"Any communication between the two cores has to be done over the external FSB, and obviously, core-to-core communication over an external bus is slow. "
AMD Dual Core
"Instead of having all communication between the cores go over an external FSB, each core will put its request on the System Request Queue (SRQ) and when resources are available, the request will be sent to the appropriate execution core - all without leaving the confines of the CPU's die."
Anyways... is 2 > 1? Depends on what you do. If all you do is play games then no. If you fold? Yes.