Some questions regarding DDR (rated) speeds.

If the motherboard supports/recommends DDR-400 (PC3200) and you use DDR-333 (PC2700), what are the usual results -- assuming you are using fairly good quality RAM, such as Cosair/Crucial/OCZ, etc.? Will it even POST successfully, or does this depend on the motherboard (manufacturer, quality, etc.)? Will it just slow down the whole system to DDR-333 speeds? Will it even be stable? Can you somehow force the system to run DDR-333 at DDR-400 speeds (not sure if this counts as overclocking the RAM)?

Can anyone provide any good external links that address DDR RAM speeds?

Thanks,