when ever a game comes out with a new game engine, you are going to get something innovative.
Battlefield 3 is going to be that game, were as compared to CODMW3 players are getting a patched up old Quake III game engine (aka Id Tech 3) where as ID is now out with Id Tech 5 on the new Rage game.
in more technical terms Frostbite2 is made to use on 64bit processors using DirectX 11 and CODMW3 is still 32bit DirectX 9
for the layman it's Battlefield 3 will NOT work on Windows XP and CODMW3 will still work on old technology of XP... this is because DirectX 11 is not for windows XP and only works on Vista and Windows 7.
with this i hope all the COD posts that show up in the form will realize that they are getting the same old COD game as before just patched up with a new name, were as Battlefield 3 we are getting a something new and innovative in the world of FPS games.
Battlefield 3 is supperor in software game engine technology
you can research and learn this info for your self, if you don't believe me.