Fifa Soccer? Compared to Halo 3?!! In my own opinion, of course you should trade it if the store will even do that for you. You will probably have to pay some money towards it, too, as your game is used and you want a newer, much hotter game. This is just my personal opinion and I don't care much for sports games so I may be biased.
On a different note, how well do you like Fifa Soccer? And now, how well do you like shooter games like Halo 3? You shouldn't buy a game JUST because all your friends have it but because YOU like it more. Who cares what your friends have and like? Your likes are more important than others' opinions. Buying something just to fit in with others would just be giving in to peer pressure and you would never be truly happy yourself as you will always be trying to please others.
