Hello everyone.  I am just about to buy and Xbox 360 and I only have enough money for 1 game (spending to much on booze lately).  Out of all the games I could buy, I have narrowed my list to 5 different games. They include:   
-Tom Clancy's Rainbow Six Vegas 2 
-Call of Duty 4: Modern Warfare 
-Halo 3 
-Grand Theft Auto IV 
-Gears of War   
With these different choices, what game should I buy.  Also, if there is another game I should buy instead of one of these, please let me know.  Thank you very much.