Well then it would probably be a better thing since you are overclocking to get the DDR2 1066. At least that way you can assure yourself you wont be running outside the ram specs.
But as far as not overclocking, save $5 and get DDR2 800.
You dont get it. Like I have said in my post, there is no real performance gains from running your memory that fast. It shows in synthetics but barely anything else. Its all over the net my friend, please look around.
EDIT: I just saw your ninja edit in there about your experience. First of all, Your CL went down as well as a 200Mhz jump in performance, thats why your "butt dyno" made it feel like a difference.
It doesnt make much of a difference. Im not blowing smoke, Im telling you my findings and the majority of the net. It sure doesnt do anything for gaming for most genre's. Think of it this way. You have a garden hose spouting 1GPM, change the garden hose to a fire hose but leave the output the same you still have 1GPM. Just b/c the pipe gets bigger doesnt mean data will miraculously move faster through it. I hope that helps.