I think 360 will have some of the best software sales ever.

look at this.

GOW 2 - 6m+

Fable 2 - 5m+

Call Of Duty 5 - 4m+

Fallout 3, Prince Of Persia, Guitar Hero  - 3m+

Banjo Kazooie, TOmb Raider - 2m+

and a slew of 1m+ sellers like Dead Space, Saints Row, Left 4 Dead, Endwar, NFS etc

This holiday will be huge for all 3 consoles imo.
Best selling game? I don't know, probably a multiplatform one :P

i agree, mutltiplaform titles still on xbox 360 side, and some best exclusive this year:
-GeOW2, Fable2, Left4dead

also hopefully Banjo sell good too, the gameplay video look impressive so far

For a year that was pretty crappy up until August, the rest of the year is gangbusters with big games. Sales should be outrageous for everything

This holiday season? Wii sprots probably followed by Wii Fit and Wii play.

Games on the Wii are obviously going to sell like hotcakes. Out of the two HD systems the 360 lead games are going to outsell the PS3's this holiday season. At least this season was wayyyy better than last year for PS3.

I'm predicting on old games' sales, as nobody does that. Please quote me and point out my mistakes.

I see something ala

Mario Kart Wii - 4.3M  (ending at 13M by the end of the year).

Wii Fit - 5M  (ending at 14M  by the end of the year).

Brawl: 2M  ( ending at 9M )

Galaxy: 2M  (ending at 9M  ahead of Brawl)

M&S Wii: 1.5M  (ending at 7M )

GTA IV combined: 2M (ending at 12.5M)

Halo 3: 1.25-1.75M, at 9.5-10M by the end of the year)

I expect you to be too high on most if not all of those titles.

- I do expect GOW2 to be the highest seller, but the first one didn't even get to 6 million, so to expect the sequal to get to 6 million in less than 2 months seems a bit optimistic.

- Fable 2 is off to a good start, but since 360 games are usually very frontloaded we'll have to see how it continues.

- I can't see Call of Duty 5 getting close to the success of CoD4 last year. First of all because I expect CoD4 to be the better game and the second reason is because I expect Gears 2 will be the big shooter on 360 for the holiday.

- Fallout 3 is an RPG, looking at games like Mass Effect and Oblivion 3M in 2 months once again seems very optimistic.

- When is the last time a Prince of Persia game sold 3 million copies on a single platform, let alone 1 month? 

- Guitar Hero 3 didn't get close to 3 million at then end of 2007.

- As for Banjo, given the special direction they took for the game and the userbase on the 360 I have yet to see it will be a success.

- A Tomb Raider game hasn't come close to 2 million on 360, so why expect this one to be a lot more successful?

As for PC games:

WoW: WotLK - 7m
Left 4 Dead - 5m
Call of Duty 5 - 4m
GTA IV - 3m
Fallout 3 - 3m
Peggle nights - 2m
Scared 2 - 2m
Braid - 1.5m
C&C: Red Alert 3 - 1.5m
Football Manager 2009 - 1.5m

The biggest selling new games will be multi-platform game titles.

Biggest selling new exclusive games on Nintendo Wii: Animal Crossing and Wii Music.

Biggest selling new exclusive games on PS3: Little Big Planet and Resistance 2.

Biggest selling  new exclusive games on X360: Gears of War 2 and Fable 2.