>Start the task manager. In the "Precesses" tab right click on some process running, some of the last context menu items is "select affinity". Almost all processes will have cpu 0 and cpu 1 checked. You can force one of your exe runs on one cpu, the other on the second. But normally it's the job of the OS to balance cpu usage and it might get the idea, that your two exes will run best on seperate cores. I think you're better at leaving both cpu's checked, but just give it a try and see what's faster.
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As Olaf already explained the manual version in greater detail than I would have, let me just add that there are WINAPI calls (get/set process/thread affinitymask) which should do the same programmatically.

HTH

thomas