With regard to COD4, it's not even 2:1 worldwide.

The 360 had relatively many shooters, Halo 3 anticipation and also Gears of War attracted shooter fans (like the original XBox did) towards the platform. COD4 is the 360's second best selling game after Halo. For the previous Call of Duty 3 the 360 had more than a 4:1 sales ratio compared to the PS3 version. The PS3 install base has grown a lot and thus the sales ratios are much closer now.

Despite the huge PS2 install base advantage I think the XBox version of Call of Duty 2 may actually have beaten the PS2 version for the US.

With regard to multiplayer, IMO free connection and near lag free servers are most crucial. In game voice chat like in games like Resistance or Motorstorm can be useful or just 'cool', typing messages would be too distraction for me without a full size keyboard (popup boxes are annoying as well) and sitting behind a desk instead of on the couch.

I don't think Live has that much more to offer over PSN features, Home and future firmware updates may well end this illusion.

On launch day COD4 360 = 1m, COD4 PS3 = 0.4m (more than 2:1), R6V2 360 = 0.55m, R6V2 PS3 = 0.18 (3:1). Now weekly sales legs are still 2:1 for both. Fine its not 4:1 as I previously mis-stated, I apologise for that, but didnt you argue that legs is important as well, when clearly the 360 has more legs on multiplatform multiplayer games with shooter elements, and maintaining them even on Week 20 for COD4. GTA4 is a multiplatform multiplayer game with shooter elements. See the pattern? So multiplayer is not a weak argument. We can argue all night about Xbox Live v PSN, but the fact of the matter is when a game has multiplayer it sells better on 360, above the 1.6:1 HW install base.

@ EaglesEye379

I expect the 360 install base advantage to largely melt away this year.

Oh please. Of course the attachment ratio will be higher on the ps3. Thats because its userbase is smaller and thus less diverse. The 360 version will outsell the ps3 version like 99% of other multiplatform games. GTA isn't massive in Japan so its not going to be like devil may cry which only sold better on the ps3 because of japan.

60/40 splits seems about right to me WW.

Considering:
1. PS3 is slowly gaining more ground every week.
2. GTA has historically been a PS heavy game so many who know very little to nothing about consoles will just instinctively buy a PS3 for it.
3. 360 has the extra content that will be discussed in shop when people are comparing then with the sales clerks and it has been advertised a lot.

Er if you are trying to get me to admit that PS3 hardware is up then er ok PS3 hardware sales is up. I didnt think this was the point. When COD4 launched, PS3 and 360 gap was 7m, now its 6.4m. Er great. This is not a considerable catch up as you put it anyway.

I thought we were talking about software units. Even with the gap, we are talking about outselling ~50k every week at 2:1 ratio, even at week 20, and in total sales, we are talking 2.5m software sales units difference. This ratio is still above PS3:360 HW, get it? 2.5:1 launch vs 2:1 legs is not a catch up, its massive legs for 360, trust me. In 20 weeks time after GTA4 comes out, how is this current trend as you said in your OT going to cause a significant lead for PS3 version. As I said in earlier posts, even if the gap closes to 3m, the software isnt going to catch up.

There are only 4 PS3 multiplatform that is slight above 360, DMC4, FIFA08, Pro Evo 2008, and another one cant remember. We all know the reasons why and its not a trend.

MikeB, what carrots has Sony tossed PS2 users to upgrade to a PS3? First, Sony removes the reason to get rid of their PS2 and forces them to keep their PS2 around, especially if they want to play the games mentioned. Second, Sony sold many, many more PS2s when it dropped below $199 - so you are assuming the masses will upgrade to a console that is over $399 and buy all new games? Hmmm ... Third, have you ever admitted in a VGChartz post that there's any good in the 360? 

I'd say more like 65/35 GTA4 sales for the 360/PS3 initially and then the PS3 catching up to about 50/50 later in the year, possibly surpassing the 360.

 According to VGChartz GTA: San Andreas sold faster than either Devil May Cry 3 or 4 for Japan.