Hi guys I have the choice between a Radeon 6870 (for $139) or a GeForce 560 Ti (for $183). Is the performance that much better on the GeForce to justify the $40 premium? I'm also only gaming on a 19" monitor at 1280x1024.All i'm looking for is to get rid of the 'shimmers' on my Radeon 4870. Do the newer Radeons still have this problem?