If that was true you might as well run PC2100 in an Athlon 64 and use a divider in the same sense. Point being, you want to maintain a 1:1 ratio whenever possible, otherwise your FSB has to wait for your RAM or vice versa and you won't notice as much of a performance increase. Look at 3-4-4-7 and 2-2-2-5 RAM running at DDR400 speeds, you'll notice a minimal bandwidth difference because memory timings are literally nanoseconds and the human brain won't detect the difference. 1T and 2T is of course different but you want 1T anyways and that's a different issue.
Intel C2D E6320 / AMD Athlon X2 3800+
Gigabyte 965P DS3 / DFI nF4 Ultra-D
2GB OCZ Gold PC2-6400 / 2GB OCZ Gold PC4000
eVGA 8800GTS 320MB / eVGA 6800GS 256MB
150GB Raptor / 74GB Raptor
2x500GB / 320GB
OCZ GameXStreme 850w / OCZ StealthXStream 600w