No, there's nothing worth upgrading at this point. The 6800 is the 5800's equal. You wouldn't notice a difference in performance.
Maybe the upcoming Radeon 6900 series or GTX 580 will be worth an upgrade for you, but they could very well be more than $350. Just save your money for the next generation.
He right. The 5850 is faster then the 6850 and just a notch slower then the 6870.
tweakboy said:A good suggestion was going SLI