Its just a matter of when either way. As others stated MW2 is outselling Halo 3 by a modest amount every week, plus you factor in two things - Halo Reach and Call of Duty "Vietnam". Modern Warfare 2 will still sell because of It's setting (not everyone enjoys World War 2 shooters, look at Call of Duty WAW sales. I know it may be set in Vietnam but it still won't be "Modern), and it will outsell Halo 3 because of Reach as well (I'm assuming most people will go the Reach route rather then Halo 3 since that would be the latest/greatest Halo experience).
So in the long run we could see Modern Warfare 2 passing Halo 3 by my guess of 2.5+ million - maybe more.
It's just that simple.







