Intel's Core 2 Duo series are the best dualcores on the market right now.
Even the lowest model, the E6300 runs circles around most of AMD's X2 series.
It's pretty cheap too (180ish).
I think AMD's new chip still got burned by Intel's Extreme Core, but I don't really remember the specifics.
Both are very nice for overclocking, but right now, Intel's are much better overall.