I have 2 sticks of 2gb DDR2 rated to run @ 1000mhz with timings of 5 5 5 12 powerd by 2.1v. My E6600 is OC'ed to 3ghz(9 x 333)and my divider is 2:3.

I've heard that a 1:1 divider is the best option... why? If I go with a 1:1 divider and run my ram @ 667 then what timings & voltage should I use?

I was thinking that I should maintain the 2.1v setting and change the timings to 3 3 3 9/10.

1:1 divider in general is "better" because it simply means you are not sacrificing ANY memory bandwidth during your OC. Anytime there is any divider put in place this generally means that there could be a few Mhz that you are unable to use because your CPU is at its celing and thusly the RAM cannot be upped anymore (make sense? I rambled a bit).

In regard to your 2GB sticks -- I really am not thinking you will be able to hit those timings (3-3-3-10) because of my personal experiences with my two sets of DDR2. Believe me I have tried EVERYTHING I could think of and I could not get my CAS 4 dominator or my CAS 5 G. Skill to be stable with a CAS 3; the dominator would boot but lockup Windows/create odd graphics articfacting within a minute usually.

What are your choices for dividers to use in your BIOS? I seems there should be something less than 1:1 but more than 2:3.....but if you were truely worried about your memory bandwidth you can always bump your multi down to 8x and toss up your FSB. Worst case scenario is that you would have to up your bus voltages.....