You can't place headshots with an inverted control scheme . Like Vivi22 said, that's the way it's been on PC FPS, and when consoles started makingn this switch, that's probably when the era of PC-ports-never-being-good came to an end. I think Halo was the first game I played that did this (Wow, never thought I'd say that sentence... ) and it was weird to me at first but I'm glad this change was made.

Maybe on flight games it still makes sense but I'm glad we're at where we are now. Now we just need more games to support keyboard & mouse support like Unreal Tournament III on PS3 (crosses fingers...)