@ erikguy
Xbox 360 CPU: 3 main threads, and 3 secondary threads.
CELL: 8 main threads, and only 1 secondary thread running on the PPE.
In terms of peak processing potential that's just 3 cores (Xenon, XBox 360) vs 8 processors (Cell, PS3). 2 threads on the PPE and one thread per SPE giving you a total of 9 hardware threads. Software threads are not limited so you can have as many of these as you wish!
A single core CPU allowing for 2 hardware threads does not equal to two of these CPUs running a single thread.