Hey sharky, I can show you a few of the useful tools VGChartz has to offer.
If you go here
http://www.vgchartz.com/weekly.php
You can see the weekly software sales, total software sales and attach ratios (these figures aren't fully acurate, but they're close)
Total software sales
Wii - 177 mill
360 - 157 mill
PS3 - 82 mill
So no, they don't infact sell more software