There's no doubt about it - for nine out of ten scenarios, the Intel Penium Dual Core E5200 will yield the best value, as long as you can heavily overclock it. If only AMD's Athlon X2 7750 Black Edition was happy to reach 3.5+GHz stably it would yield a far more competitive or even the best value processor in more tests.
For those that want to stick with AMD, the Athlon 5200+ also looks like a good possible choice for extremely cost concious individuals, but if that's the case, we would actually point you in the direction of the 4850e instead. In the performance graphs it may sit at the bottom, but we know it loves extra HyperTransport, and at just a 45W TDP it has oodles of thermal overhead meaning 3GHz+ is very doable. This would likely yield 6000+ or greater performance, but for a fraction of the cost, dropping it into the green area in many cases.