So what will it be?

Halo 3 is 1.59m away but has sold over 1m WW this year and could do several hundred thousand over christmas alone leaving just ~1m to go it will make it for sure but when. end of 2009 most likely as it will get boost from "Wars" and "Recon".

Could GOW2 sell 10m? it will be hard to get almost a 200% increase on the original. but there are a lot more 360's out there. probably 8m.

i cant see anything else doing it at this stage

Your right it will be betweeen halo and gears but since halo has a huge start it will be halo

Also halo is undertracked here its probably around 9 million by now

halo 3 is the only one with a decent chance. It is likely to hit 10 million on vgchartz around the launch of recon because it will have had boosts from both halo wars and halo recon.

Gears 2 will be lucky to hit 5 million. It's been underperforming compared to GTA4 and Halo 3.

GTA4 is the only one with a chance as it has worldwide appeal, not just american.

if halo 3 doesn't, nothing will. (except halo 4)

Halo 3 will be the first. Depending on how long this gen lasts, and when they hit bargain bin prices there may be an outside chance for GTA4 and CoD4.

I think it's still too early to judge Gears 2's legs. Some people may write it off since the first only did a little over 5M, but CoD2 and 3 each only did a little over 2M whereas 4 is a beast, so Gears 2 is a wild card that could go either way. Again, it all depends on how long this gen ends up lasting.

It only needs a 100% increase.

Gears sold uner one million copies its first week, and it managed to sell over five million copies. Gears 2 will easily obtain five million. 

Halo 3 will easily be the first 360 game to obtain ten million copies sold. There is no challenger. 

halo reckon