People buy a Wii, play Wii sports and maybe another couple games for a few weeks, and then it collects dust. Xbox owners subscribe to Xbox live and buy new games quite frequently.
Total Wii games sold as of June 1, 2010: 573 million
Total Xbox 360 games sold as of December 2009: 353.8 million
Total PlayStation 3 games sold as of June 30, 2010: 315.3 million
So yes, the Wii is beating the crap out of the Xbox. Americans don't realize that the Xbox only does well in the US. Europe and Asia are a tough market for Microsoft.
Xbox users pay to subscribe to Xbox live. Microsoft makes money providing the same service that Sony and Nintendo give away for free, and more people use it.
I call B.S. The majority of XBox purchasers buy a bundle. Whether it is the Kung Fu Panda / Lego Indiana Jones (this my Bundle...my XBOX came with 2 games) or the Left 4 Dead 2 Bundle or the Halo: Reach Bundle.
Usually if you are buying an XBox console and NOT buying a game, you're buying a replacement XBox because of the Red Ring Of Death.
And everyone who trashes Wii games forget about games like Super Mario Galaxy. Games like that can give you three months of solid playing if you want 100% completion. And no worrying about having to rush/grind through the game before another comes out so the online play is empty.
Asia is a tough market for Xbox. Europe is just fine.
PS3 in Europe as of August 17, 2010 : 16 million
XBox 360 in EMEA (including UK) as of November 13, 2009 : 10 million
Sources : http://www.computerandvideogames.com/article.php?id=260424