I went from SLI260 to SLI275 and the only the biggest diff was it ran cooler. About 3 months ago, I went from 275 SLI to a single 5870. I frame rates improved on all tests I ran, but not more than 5 or 10%. However, again the biggest improvement was temps went down further. If your not running at least 1920x1200, your not gonna see a big diff between gtx260 sli and 5870. I'm assuming based on your question you havent purchased yet and you dont have an existing 260. If that the case, always go with 1 card solution. Get the 5870