Try a GTX 570, GTX 580, GTX 670 or GTX 680. While the Radeon hardware is great, the drivers probably have a lot to do with your issues. I waited a year for the laggy stutter to be corrected in BFBC2 when I had Radeon 5850s in crossfire. After none of the monthly drivers fixed the issues, I picked up a GTX 580. The performance was so great, comparatively, I picked up a second 580 two weeks later to see if it the stutter I had with the 5850s was the norm with multi-card setups. I found it was not.