I don't know about your numbers but most people have said that it will be close over the holidays. The thread is not addressing just this holiday season however, and is asking about lifetime sales of the titles.

@Cursayer2

Are you being sarcastic? I mean really...because its Mario!

Seriously, I don't know what you have been following but it seems the general consensus is that SMG will have a larger install base to sell to and practically no competition to go along with its huge name recognition. This is in stark contrast to Halo 3 which will have a smaller install base to sell to, tons of competition with Gears of War, Call of Duty 4, Haze, Brothers In Arms, and I think there was one more game I am forgetting. Add to this that desctructoid which is a very 360 friendly site, gave SMG a review in which they say things like....

• "Seriously, there was a sequence when you are climbing on the back of a giant bee (yeah, that is as amazing as it sounds), and the fuzz on the insect is so well-rendered that it actually looks like you are playing an Xbox360 game. "
• "By grabbing the stem and shaking the Wiimote up and down, Mario rides the stem at breakneck speed all the way to the top, shooting him into the air. To say this is satisfying is a complete understatement. The three of us actually squealed in glee when doing this for the first time. And if you know Dyson, you know he never squeals in glee."
• "I will get this out of the way right now. I may have had more fun with those two levels than I have had with any other video game in the last year. Yes, I know, that is a pretty hardcore statement, but it really is true. There is so much creativity in each section of Super Mario Galaxy that it almost puts all other games to shame."
• "I have to say that Super Mario Galaxy is as close to perfect as games get and a huge testament to what the Wii can do."

..and there are other similar reviews like this one all popping up every day from E3. So for me at least it is hard to see how the statement that "Halo 3 will sell more, because it's HALO..." really means much of anything.  But time will tell..

EDIT: PS - I am sure Halo 3 will be a good game and probably enjoy some solid sales, after everything I have heard about them taking time to make sure everything is right this time it better be =)  I just question wether the lifetime sales can really hope to be on par with SMG. 

Halo will outsell Mario Galaxy this year.

Lifetime, I think it will outsell it too but it will be closer.

Also, in the US Halo will outsell Mario Galaxy easily, double if not triple its sales.

The reason why it's even debatable is because Japan doesn't like FPS games or the 360 generally.

Galaxy.

like any1 wants to play little kiddy games.

japans not going to buy nothing. halo 3 is going to win ne ways

Hey blue. Glad to see your starting off on the right foot.

Like others have said, Halo 3 will be huge, but it's target audience is limited. Many people dislike FPS, and even if they do like them there is so much competition. SMG on the other hand is being described like a game that everyone would want to play (well maybe not die hard PS-360 fans, but still).
I'm really curious about Brawl though... so much raw potential...

Halo: ~10 mil
SMG: ~16 mil
SSBB: ~7-20 mil

so mor people like to jump on shit than shoot aliens with great graphics

wow. great world

 You make some good points, how come you were banned ?

cuz this site is all nintendo fanboy kiddies and they ban ne1 who likes sony

 then why are you still here if you believe that?