Halo Wars and Resident Evil 5 (X360) will both sell more than Killzone 2. I am assuming Killzone 2 will be selling at the current PS3 COD WAW pace.
Look, if Fable 2 and Crackdown can both sell great because of a Halo beta and Halo Armor, How many copies can a game that is a Halo game, and have the new HALO 3 Map pack included in the LE can possibly sell?
Also, Resident Evil is a much bigger franchise that KZ and will no doubt sell more just on the x360 version.
Halo Wars and RE5 are 3 plus millions sellers on x360 and I can see Killzone 2 doing an amazing 2.5 - 2.9 millions lifetime.
Either way I have both sytems so I really don't care as I am getting all the great games.
Be a gamer not a console hater!