I think Halo Reach will sell less then Halo 3.
The reason Halo Reach has so many pre-orders is because it has the most hardcore fanbase. I really doubt the First week numbers for the game will be much higher. Also what you got to consider is people were purchasing a 360 for Halo 3. Those people will still have 360's, well most of them.
So it is fair to say that most if not all Halo fans already own a 360 so the hardware isnt going to have a huge boost eva.
I think Halo Reach is going to have worse legs then Halo 3 due to a few reasons.
People already own halo 3 and odst and may feel they dont need another Halo game yet.
Call of Duty has also become a huge franchise in the same genre. So it may cut of some of the sales from Halo.
360 having a large diverse library. Just because a game is old it does not mean it stops selling or is no longer competiton.
Plus some people will still be purchaseing the other Halo games over Reach because of them being cheaper.
Nobody's perfect. I aint nobody!!!
Killzone 2. its not a fps. it a FIRST PERSON WAR SIMULATOR!!!! ..The true PLAYSTATION 3 launch date and market dominations is SEP 1st 
