Now that the Steam sale is over and I finally downloaded all my new games for cheap (ehehehe....), I am somewhat ambitious to upgrade my video card to really get the most out of all my games. Some highlights include Skyrim High Definition, Arkham City, The Witcher 2, Dishonored, and so forth. I really want to maximize, as best as possible, these games. Above all I want to make the computer as future-proof as possible within my budget, as I don't foresee buying a major new part for it in a couple years (excepting replacements to dead parts). Here's my current setup: http://pcpartpicker.com/p/yRKi. My CPU is OC'd to 4.4 GHz, if that is necessary, and I'm not looking to overclock a GPU.
I am thinking about a GTX 660ti or a 670, but I wonder if my Power supply will work with it? I can JUST stretch my budget to cover a 670's price, so I'm not really interested in going above the $400 (US) mark. I also noticed that a lot of my games seem to be developed with nVidia in mind, so I've been looking into those, but I may not turn down another AMD card, given the latest Catalyst drivers.
What should I upgrade to, assuming a roughly 350- to 400-USD budget?