SO, WHY DOES THE XBox 360 have three cores? As you know, three is not considered a 'nice' computer number, but then again software doesn't seem to care, especially if it is coded for the hardware. No, there had to be a deeper reason.
Last week in a meeting with an XBox360 engineer, the truth was revealed. It seems that flat out, the graphics pipeline takes two cores, both threads from each, to 'fill'.
If you code things right, that will leave you with a single core for the 'game' parts, basically everything but graphics. According to another MS person, a single core is more than sufficient to make a great game, and you have effectively double that if you are exploiting every last drop of GPU capability.
It seems like they thought the balance of the machine out very carefully, but the three cores bit still seems to be a bit odd. Time will tell if they did the right thing for the right reason, or if it will end up as a one off computing curiosity. The more I learn about the hardware, the more I lean toward the 'right'. µ