Grand Theft Auto IV, first week sales: Halo 3 is still the champion

Now that one week has gone since GTA IV release, the statistic for the GTA IV sales the first week has been released on vgchartz.com.
If we take GTA IV on both consoles and compares it with Halo 3, then GTA IV would of course win, but since Halo 3 is exclusive for Xbox 360, should we not compare GTA IV side by side with Halo 3 one console at a time?
Well then it shows that GTA IV has sold about 3.3 millions copies on Xbox 360, and about 2.65 million copies on PS3.
The conclusion is still that Halo 3 is the leader of first week sales with a crushing 3.75 million copies sold the first week