I was wondering if this build could play at a reasonable frame rate on max or high settings @ 1440p
http://pcpartpicker.com/user/b0wl/saved/2E1v
If you're getting this build for gaming, I think you could increase performance in the graphics card and drop down on other parts and get similar performance everywhere else still but immense improvements in the graphics card. I personally own a 280x (Will link page with my benchmarks and reviews) and I love it but I think you could spend your money more efficiently. If you want any help just ask me and I'll make you a part list.
The power supply will melt [ or at the very least its below the recommended minimum for your graphics card ]
He's got a point. If you're planning on doing any overclocking you need a bigger power supply. That machine should use about 400 watts but under full load it will go up, I would recommend getting at least a 600 or maybe a 750 or an 850 so you can crossfire in the future.
The earlier suggestions are all correct. I would go i5 and a little cheaper ram and go for more gpu. Power supply i would suggest having a little more than minimum recommended and make sure it has enough on the 12v rail.
This would get you similar performance in all parts but MAJOR increases in the graphics card. I think that this is the best build you could go for at your price point