What are you talking about? There are heaps of benchmarks on the X2 6400+ on the net, you just have to look.
You'll probably hate me for posting the following article (be warned) http://www.xbitlabs.com/articles/cpu/display/intel-wolfdale_6.html#sect1
That's neet, however, the OP wants to know how is his 6400 going against the 6400s benchmarked on the net.
I assume we already know that the core 2 are faster than any Athlon X2, still not a lot faster. Wait... those 45nm really rocks.