This is kind of a silly thread.
KZ2 is basically unbeatable, with regards to technical quality, by any cross-platform title. Even as an exclusive, its like that only a few titles, including a would-be Killzone 3, will surpass it.
MW2 is *amazing* in that it is cross-platform (!), thus sacrificing many visual issues to the "lowest common denominator" of the two HD consoles, and it still looks awesome. It doesn't best KZ2 in terms of visuals, however. -- anyone who says otherwise hasn't actually played both, or is wearing heavily tinted fanboy goggles.
If IW was willing to drop the framerate of MW2 to 30 fps, and improved upon a bunch of their visual tech, then we *might* have a decent comparison between it and KZ2. As is though, its no contest, on a frame-by-frame basis, or even in motion, despite the framerate differences.