I know a few people who said they would get a 360 when Fable 2 comes out. Just like the people who waited for Halo 3 to get a 360. It should sell some systems.
Gears 2, people alreay bought to play Gears 1 or bought when the price dropped on the 360.
LBP will eventually sell with word of mouth. moms will probably buy along with a PS3 for kids.
Resitance probably won't, for the same reason as Gears. people already bought to play Resistance 1.