I would go with the 7770 if I were you. It consistently out performs the 650 in games. nVidia doesn't have a card to compete with the 7770 at the moment for that price.
Another thing to consider is the 8XXX series from AMD is going to released soon. You could wait and see if there are better similarly priced options when they come out. But if you can't wait get the 7770.
16x Anisotropic Filtering
All settings maxed out