woltej1 :
is your 660 struggling at 1600x900? And a 770 is overkill for what you need. a 760 would suit you better and save some cash.
Exactly what I was going to say. If I look at the games you're playing, your 660 should max all of them at 1080p. Really no need to upgrade.
There's no such thing as future proof. If you don't need to upgrade now there's no sense in doing it. Usually I wait for a game that I really like to struggle for me to justify an upgrade. Then I get the best bang for my bucks on what is currently on the market.
The GTX-770 you're looking at will cost half the price in one year. So why throwing your money at the window and get it now when you don't need it? There will also be new GPU models in a year or two that will outperform it for the same price if you are ready to spend that much. Either get the 770 for half the price, or the new 870 for the same price, but wait until you really need to upgrade that's the only advise I can give you.