How important is RAM speed

[Finners]

I'm planning on building a system to have a play around overclocking with but i would like to know how important RAM speed is

the MB i have takes 800 & 1066 DDr2

Do i need the fastest ram or will i get away with 800mhz,

I'm not 100% how this will effect my CPU overclock if i leave my memory at stock speeds

Thanks

[stawte]

There are 800mhz memory modules which OC very well and there are which don`t. But since there is no big price difference between 4gb kits @ 800Mhz and 4gb kits @1066Mhz, I would go for the second option.

The speed and timings are important in OC, but inday to day use you could barely see any difference at all.