@Frozen... and indeed Mrfenix.
Please don't use that odd method (that annoyingly game pages use) to combine sales.... either split them by region totally, and look at the seperately, or look at them in totals.
Here is the graph for total sales of both games:
http://vgchartz.com/swlaunch.php?reg1=All&game1=New+Super+Mario+Bros.+Wii+-+Wii[35076]®2=All&game2=Call+of+Duty%3A+Modern+Warfare+2+-+PS3[28847]®3=All&game3=Call+of+Duty%3A+Modern+Warfare+2+-+X360[28848]&weeks=15&weekly=1
As you can see, NSMBWii has beaten both single SKU games for it's 2nd, 3rd, 4th, 5th, 6th, 7th, and will manage it for the 8th (and indeed all future weeks most likely) However, combining the two versions of Modern Warfare 2 sees it beat NSMB for Week 2 sales, as well as week 7 sales (although that is because week 7 for Mario was the week after Christmas, while for MW2 was the biggest sales week of the year)