Or you could just say that there were 6 million 360s shipped by the end of September, and guesstimate those units sold through around PS3/Wii launch. That 6 million lead has shrunk to 4.25 for Wii, and grown to 7+ for PS3. Close enough for government work.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.