DDR2 Memory Confusion..

[Admiral Huddy]

I've not had much dealing with DDR2 and i'm really getting in a mess understanding the CPU/Memory compatability, so I need some help..

For example, I'm failing to understand why a CPU which has a FSB of 1066 MHz is compatable with memory that runs at 800 MHz (PC2-6400)

I thought I had it cracked bu I'm still a little confused.

Can some one help please...