You may want to invest your money in a better monitor. I couldn't imagine spending the extra money on a 965 to skimp on everything else. :P Get the 5850 and spend money on a monitor with at least 1680x1050 (preferably 1920x1080).
You can get a good 1080p monitor for around $160.
Performance wise... GTX 260 SLi > HD 5770 CrossFire > HD 5850
Cost wise... HD 5850 < HD 5770 CrossFire < GTX 260 SLi
With single cards:
Performance wise... HD 5850 > GTX 260 > HD 5770
Cost wise... HD 5770 < GTX 260 < HD 5850
Obviously you're getting what you pay for. It's important to note the HD 5850 and HD 5770 CrossFire support DirectX 11 and will use less power/output less heat. If you're sticking with that monitor, CrossFire/SLi is overkill at that resolution.