i had an nf7-s and a 2500 barton (locked) @2.2, went to a mobile that did 2.6, you don't really feel the difference, finally bought a venice 3000+, in gaming a 1.8 amd64 is around a 2.5/2.6 barton, certain tasks will be faster with the higher clockspeeds but it isn't by much, overclocking the 3000+ you should be able to easily hit 2.4, think about the msi neo2 agp board and find a cheap 3000+
its not so much that it benchmarks higher, its just that the fps is a lot more constant, it never really drops significantly