napster88 :
Therefore nvidia or ati? 7970/r9-280x, or the 760/670??
Disregard the newer AMD cards since I think they're slightly more expensive. There are currently some issues being sorted in driver that may skew benchmark results (temperature-based throttling) for the new AMD cards. Not saying don't get one, just that I don't know if I can accurately give advice until some cards are re-tested with the latest drivers.
Then look at the benchmark I provided in my reply above. I believe a STOCK 760 is just below a 670 (barely).
Again, be very careful to factor the following:
1) Total cost
2) SUBTRACT Games value
(Would you buy them anyway? Or sell? What is the Steam cost of each game? (NVidia games are all new).
3) PERFORMANCE (see benchmark)
4) GPU frequency (apples-to-apples; can't compare 850MHz HD7970 to 1000MHz/1GHz HD7970 for example).
5) Cooling solution: noise/overclocking (some cheaper cards have noisier fans)
6) Customer reviews (see if a card is known to fail, or is much noisier than other similar cards).
7) AMD vs NVidia features (PhysX, Shadowplay, G-Sync for future monitor)
8) SLI vs Crossfire (if a future issue)
My advice is take the above advice and compare cards on PAPER. Concentrate first on value, including the games.
I'm not going to recommend a particular card anymore, and if you decide on an HD7970 at least get one with a great cooler, but I encourage you to take a bit of time and lay out all the details and make a really informed decision.