The 560 isn't enough a jump over the 460, particularly the Superclocked model by evga (I've the same card). If you are going to upgrade to a single card solution, you'd only really find value in a 570/6950-level, and that is only at 1920x1080 or higher resolutions. And given how close we are to the 7xxx series, if you wait you can get either a better deal on this gen, or score a solid single-card solution.
Minolta 50/1.4, 17-35/2.8-4, 24-105/3.5-4.5, 35-105/3.5-4.5, 80-200 HS APO G, 100-300 APO
Tamron Di 90mm/2.8, 28-75/2.8