Her's an article by somebody who works for Intel with an illustration showing 0 and 1 on the first core, 2 and 3 on the second:

http://www.ddj.com/embedded/196902836

I can't find any documentation by Intel or Microsoft which makes me suspect that they have decided not to document it because they don't guarantee any particular arrangement. However both companies explain how to get this info programmatically.

For Intel see Chapter 7 (especially 7.9.1 and 7.10) of the Software Developer's Manual, Volume 3A, which you can download here:

http://download.intel.com/design/pro...als/253668.pdf

For Microsoft, the following function is apparently part of the NUMA API but maybe you can use it to query a Core Duo quad:

http://msdn.microsoft.com/en-us/library/ms683194(VS.85).aspx