It'll easily outsell the 3 totals you listed. GTAIV is looking to have around a 4-5m first week. That's pretty huge, no? Considering the legs every other GTA has had, I would assume that it could wind up with a 3-4x multiplier from the first week: certainly enough to outsell what you listed.

If we add all versions of SA together it has sold over 20 million I think (the current VGC Europe numbers for PS2 look outdated to me, so I think it may be over 16mln on PS2 plus 2 for XBox and whatever for the PC). I doubt GTAIV will manage that.

It would cost a lot to port it to the wii. I don't think its going to happen.

The 360 version of GTAIV will outsell HALO3 by the end of the year...

It will outsell San Andreas for certain. Presuming we're talking combined sales here and not just PS because it won't outsell GTA SA on ps3 alone. GTA SA has shipped 21.5 million copies according to Take Two so I doubt GTA IV will top that.

 actaully, I think GTAIV could at least sell 2-3 million on Wii

GTA on the Wii would do quite well. Look at the PSP.

@eliasg, while I do belive, that it is possible, I find it highly doubtfull for it to happen this year, maybe next, though the download content could spur that to happen sooner depending on what it is.

Halo 3 has several things going against it, its in a crowded field, it was released to a smaller user base, by about 5-6 million. its price will not be lowered to greatest hits for about 2-3 years... (halo 2 was 29.99 untill recently)

 Right, but Halo 3 sold nearly 4 million first week worldwide, and it's going to scrape past 10 million sold. 

I think it will beat everything but SA, personally.  

dont think so!