>> Some people think that "16 cores" really means 16 threads,
>> i.e. 4 cores with 4 threads each etc.

> Or two main cores (SPEs) and 14 PPEs?

Apart from the fact that you're confusing SPEs with PPEs, I very much doubt that Microsoft will use a chip that follows the Cell concept. Durango's (and its devkit's) CPU will most likely have symmetric cores, just like Xenon/XCGPU has.