I recommended against the GTX 260 because the HD5770 is cheaper, DX11 compatible, has more current A/V features, supports 3 monitors and uses much less power, especially at idle. It is actually the card I would recommend for your resolution. Here is one from a good brand for $145 shipped and it has a $15 rebate;http://www.newegg.com/Product/Product.aspx?Item=N82E16814102873
It will do extremely well at your resolution.
As for overclocking the processor something like 3.3ghz should be very easy to achieve even on the stock cooler and at that speed it will do fine.