Get yourself an E6600 and OC it to 3Ghz on air absolutley no problem!
You now effectively have an X6800 Cpu for the price of an E6600.
AMD have absolutely nothing to offer in the CPU market at the moment.
We get inside information from AMD being in the industry, and to be honest I cannot see anything in the pipeline that will knock core2 or Quad core off the pedastal in the forseable future.
Best of luck with your build