Yeah but part of these games' appeal on the console is that the AI, weapon damage, etc. is designed around the limitations of the controller, the slow turning rates, etc.
With the precision offered on a PC, Gears of War would probably be ruined; headshots all the time, perfect shots with missiles, perfect shots with grenades, etc.
Halo on the PC was not a bad port at all, but the slow movement and the thick-headed AI (even by crappy AI standards) was no match for me once I had the precision of a mouse.
Granted, Gears is a different animal and it will probably be very good. But I think it would just be different. The satisfaction of those good shots will be gone, almost every shotgun round will be fatal, etc.
The added options will probably be well worth a purchase though. And the mod potential...man, I was I could make a Warhammer mod for that gameplay....