667/2 = 333.5 appr0x 333Mhz. By the way, both actually resembles the DDR 667Mhz. Just the 2 is to let user know that it is DDR2 RAM. It is also to differentiate between DDR and DDR2.

3GB?

Not sure about that. But just to inform you that 32-bit OS still do not support more than 4GB RAM. And it also recommend to use only 2GB RAM for the 32-bit OS.

Good link.
Definitely, higher frequency and tight timing is good. But low frequency and tight timings not all time better than higher frequency with little loose timing then the lower frequency.

My advise try to go for 2GB pack. But it is ur choice whether VS ram or performance ram.

It is depends on the RAM module you had been used. but one thing for sure is that for 4 module running all at once, you cant get the max frequency of the ram slot. By default the frequency will get lower one step.

Based on my reading sometime ago, there is not necessarily bad thing to run at lower frequency as well as it it not necessarily good as well.

I hope you can Google a little bit to find your best solution. Good luck.

Let the timing more loose at the 1000Mhz unless you are using very good performance ram which can get the stable at the particular timing when OC-ed.

Maybe you can try pushing the voltage more than stock V, but i would suggest you check with vendor/manufacturer technical spec if anything happen.

You can upgrade the ram and use them for casual but there is no certainty that the setup will be in stable mode.

The best is, try to look for identical model ir order to get stable dual channel setup.

Go for micron chipset ram.

Check your notbook ram pin to ensure the compatibility. Different Brand might have no problem with your notebook if the specification/slot is the same.

Supposedly, the ram capacity should detect your ram as 1024 instead 1023.

for notebook, at the moment there are only mathc pair value ram available. No performance ram yet.

check you mobo manual. For instance, Asus stated on its manual to use corsair ram for stability.

DDR800 Mhz is basically will able to work with 667Mhz DDR2 RAM slot. But by default, it will run at 667Mhz instead of ram default frequency of DDR800Mhz.

Noted: Check and do research on forums to identify which model have good compatibility and stability with your motherboard.

Many Intel mobo ccan support DDR2 800Mhz or even higher frequency. But withput having OC, the default setting will detect the ram as what stated in manual.

Yes it is. By default it is stated like that as the 400/0.5 Mhz.

You can manually set to to its default factory setup to 5-5-5-12. If not stable, try to set to default Voltage. If im not mistaken, corsair model that you mentioned is well stable at 1.9V with 5-5-5-12 2T. Same like mine in my system.

Go to bios to change to this setting.

Normally by normal use, it would be Okay to run at default timing detected by your motherboard. Therefore, if you want to achieve what you deserve on having performance ram, you should set the timing to its lower timing. Of cos overclocking will enhance more performance to its, but frankly speaking there is slight faster in the timing is lower.

You will noticed this when comparing two PC running on identical setting but with different ram model and timing.

ECC is for Error Correction. You can check whether your ram have this function by navigate in memory tab on CPU-Z. It depends on whether you r mobo will able to use or not. Different mobo will have different spec and compatibility.

Im not very sure on that. Sorry.

2X1GB. that would be the better choice.

Agree, by the default the frequency clock will follow the lower frequency clock.

if you plan to OC, choose performance ram over Value RAM. Take consideration about the fact that performance ram beside OC ability, they was designed to minimize error when loading and reading from and toward the memory.