DDR2 corsair memory & overclocking

[llama_thumper]

guys, I admit I am a newbie to DDR2 and an overclocking virgin so to say, so I wanted to ask a few stupid questions -

On the following pages there's instructions on overclocking an Intel processor. Specifically, on the page I'm linking to, it refers to overclocking of memory, as I understand it(?):

http://www.tomshardware.com/2006/05/10/dual_41_ghz_cores/page26.html

I'm assembling my system but have trouble getting PC2-800 memory, specifically I would like to have "Corsair DIMM XMS2 1024MB PC2-800 DDR2CL5-5-5-12 (CM2X1024-6400)" memory. However, only PC2-667 memory seems to be in stock where I live (Austria).

What effect is this going to have? Can I, through the BIOS, overclock this memory to 820 Mhz (as they do in the article - see the screenshot?) Does the memory NEED to be overclocked in order to work fine with an overclocked CPU (from 2.6ghz to 4.1ghz as in the article with new cooler-fan, or minimally 3.6ghz as in the article with stock cooler-fan)?

Is there anything else that I'm not asking that I should be asking?

Sorry for the noob questions, but am just starting out

thanks!

 

[Rokusho]

Well memory and overclocking is pretty simpkle, but at the same time complicated.

You can uise muoltipliers meaning the memory wont really get overclocked much if done right, dont ask me how, I've only overclocked one computer to date (one I have at the moment). So im kinda of a n00b too