In most games the 6400 wins by a margin of 1 - 2 FPS and in CoD 2, it won by 20 FPS.(compared to the 5000+ on Toms CPU Chart) Most applications that I looked at the 6400 won or was very close, like in the specific one that you showed. The 5200+ is online a cache increase, which we all know that on AMD K8 arch doesnt mean a whole lot because of the IMC. On 3Dmark06, the CPU score and the Graphical scores, trade minimal blows on both, which evens them out. The price to performance ratio also was better on the C2D, so Even without OC'ing it seems that the better purchase could weigh towards the C2D simply because it appears that it is better for the price, but still neck and neck at stock speeds with the 5000 and most likely the 5200+ as well. If OC'ing is even brought into the equation at all then it is no contest and the C2D wins. Also remember that the AMD is going to require good speed and latency memory to be used to its full potential where as the C2D fairs better when you can achieve FSB and Memory sync. It is possible this could lower cost, but the difference will be quite marginal IMO, so from the facts I have seen and experienced through ownership of different parts and looking at Toms CPU chart the 6400 appears to be the better way to go. This is just my 2 cents, I am not trying to sound like an Intel fanboy, I am just trying to help. I honestly think that the better choice is C2D at this point, but either way the OP goes he/she will have a very fast chip and will not be disapointed in the performance, unless OC'ing is an option here, which it may have been stated somewhere whether it is or isnt and I just missed it and apologise, but never the less I recommend C2D, but at the same time am not saying you should not get the 5200+. I am telling what I would do if I was in his/her situation.
Best,
3Ball