Help choose RAM PC6400 or PC8500??

I am helping my cousin pick out parts and build an AMD system with the Phenom 2X4 940 processor. I know that when I built by Intel Q6600 system, everyone told me that I wouldn't notice a performance boost in the 1066mhz Ram. In other words, The 800mhz ram is going to essentially provide the same amount of performance. My question is,,, Does this hold true for AMD systems? Would he notice any real performance difference between the two. He's not running any sort of memory benchmarks and is just doing normal computing and some live TV recording. Maybe a little gaming (he bought a HD 3850).

Thanks

I'm talking about DDR2 1066 memory vs DDR2 800 memory.

this is ur third thread about this...have patience please. anyway you should run your ram at a 1:1 ratio and unless you plan on overclocking 800mhz should be fine. also if therer similar prices just get the faster ram