ETA: My memory says it is DDR2 800 (PC2 6400).
But my motherboard says FSB of 1066/800MHz.
And my CPU says FSB of 1066MHz.
So which am I (or should I be) running my FSB at?
Your cpu saying it is at a 1066MHz FSB is what it should be at. That is normal/correct/stock setting. Your motherboard saying FSB of 1066/800MHz, is that in the specs, or in the bios? I assume that's the FSB processor support for your motherboard. Your memory speed is separate of the processor speed but it is good to run at a 1:1 ratio. Since your memory is DDR2 you could underclock it to 533 and you would still have a 1:1 ratio for FSB to memory speed(533*2 = 1066).
I wonder what would perform better: DDR2-800 at stock timings @800MHz or tightened timings at 533MHz (1:1). Somebody needs to test it. Without tightening the timings the 800MHz speed would win for sure, but if you tightened the timings it could get interesting.
short answer....yes, the cpu runs stock 533 and not many push them past 3.6. That would be DDR2 800.
By the same right...there is no such thing as overkill....if you want it...get it....you can run out of sync and use it to its full 1066 fsb is you want(there will be almost no noticeable improvements tho )
you can get it and run it as lower speeds with tighter timings...or lower speeds with less voltage and save on heat and power(not much but still some...)
You get the same ram for an e6600 or Q6600.....they use the same 533(266 in the bios) fsb