One thing I can tell you, is that when I was trying to gt my 2.3 ghz processor computer to run the sims 3, the tech support said no you need 2.4, obviously that wasn't the case, the store your buying from, can you return the game? Also game debate says you can run it,
http://www.game-debate.com/games/index.php?g_id=1400&game=Modern%20Warfare%203 and this says no http://www.geforce.com/games-applications/pc-games/call-of-duty-modern-warfare-3/system-requirements, remember I don't think system requirments are 100% spot on, look those to are completely different. However it's odd that I can't find the original system requirments..... Hope you got something from that, I think the answer is, it's up to you. Can you run most other AAA games? Other COD games? Arma 3 or any other big time fps or graphics heavy game? Because its not like your pc will just not launch the game if you don't meet the system requirments, it might just crash or your pc will overheat.