ddr2 - RAM memory : is memory speed (Mhz) limited by the fronside bus speed?

I would like to increase memory for my old dell inspiron 6000 and put it to the max, 2 x 1 Gb.From the specs review on cnet.com I see that I have :

DDR2 SDRAM

SODIMM 200 pin

PC2-3200 / 400 Mhz

On crucial.com I can find what I want, but only :

PC2-6400 / 800 Mhz CL6

PC2-5300 / 667 Mhz CL5

Compatibility is guaranteed as they say and they no more propose DDR2 @ 400 Mhz. Questions are :

Do you think I can upgrade with one of those ?

Or is the frontside bus speed determinant (533 Mhz) ?

Answer

I think that RAM module specifications usually state the recommended (or highest stable) settings on which the module should work. So it is always capable of running on lower frequency or higher latency then stated (depends on your CPU and bus settings in BIOS). What matters is if it is DDR2 or DDR3. That must match.
Hope I don't say nonsense, but so far it was always like this in my experience.