I would wait a week or two for the new cards from ATi and Nvidia to come out with official benchmarks.
You might be able to sell your current card and make enough money to buy the new ATi .. It might do 20 - 40% better than what you have now all in one gpu.
You are about to answer a thread that has been inactive for more than 6 months. If you still wish to proceed, please ensure that your posting is original and does not duplicate or overlap any prior responses to this thread.