Something just to factor in:

1: 360 was released early due to it's contract ending with NVidia and the end of the Xbox. Launch and production happened within months of each other which sucked for Microsoft.

2: 360 has a lowered failure rate of 16.4 percent. Generously saying that was the case since 08 it would mean 3 million units which were sold were replaced. The 12 million which had been sold from launch had a 30% failure rate.( Thats generous, some say 35%.)Thats another 3.6 Million units replaced.

3: The Wii and Ps3 has a failure rate of 1%.

Take this into account and you have:

Wii-44.5 Million units sold

Xbox360-21.4 Million units sold

Ps3-21.1 Million Units sold

You can reference this from countless places on the internet, magazines, or pay attention to your daily news.

360 Has sold 28 million, up four million from last update,

Ps3 has sold 21 Million, up five million from last update.

And of course the Wii is up a staggering eleven million with 45 million units sold.

And lastly the Ps2 which only updates once every six months or so sits at 140 million units sold worldwide.