Confused about memory selection

Hi,
I would like some help with memory selection.
My chosen motherboard is Gigabyte GA-965P-DS3 for Coure Duo E4300.

My question is not about compatibility, since the sticks are compatible based on Gigabyte's website.
I just wanted to know the difference between the various Corsair 2gb XMS2 models. I'm a newbie regarding RAM and do not really know a lot about voltage or latency. Most of the guides I found about memory selection are quite outdated.

Basically, I narrowed it down to 3 models. I have decided to go with Corsair, since they have good reputation, but I'm not sure which one should I go for:

1) Corsair XMS2 TWIN2X2048-6400 Matched Pairs 2GB Kit (2x1GB) PC6400 DDR2-800 CL 5-5-5-12 240-pin Dual Channel Memory ($139.99 CAN)

2) Corsair XMS2 TWIN2X2048-6400C5DHX Matched Pairs 2GB Kit (2x1GB) PC6400
DDR2-800 CL 5-5-5-18 240-pin Dual Channel DHX Memory ($159.99 CAN)

3) Corsair XMS2 TWIN2X2048-6400C4 Matched Pairs 2GB kit (2x1GB) PC6400 DDR2-800 CL 4-4-4-12 240-pin Dual Channel Memory ($168.99 CAN)

My hunch tells me to go with the 3rd choice, since its more expensive!?
But my system won't be high end. As for overclocking, it might be an option, possibly in a
year's time.

Help would be nice.
Thanks!

Any 6400 RAM will give you massive headroom for overclocking, so that's not an issue.
The only thing the 3rd option offers is tighter timings, which in all honesty you wont see the benefit of in a core2duo system.
Yeah the benchmarks may show an improvement, but you would be lucky to see 2fps out of it in games :)

Get the cheapest mate and save your money :)

All three of those would be a good choice. The third would probably be the fastest, regarding default settings. But the differences are just maybe 1 or 2%, definitly not noticable in everydays use. If you can afford it, get the CL4 sticks and be a tiny bit faster on stock settings, and have a bit more reserve for overclocking later. If you want to spend 30$ difference on something else, that is fine too. As said, doesnt make any real difference, only when going for serious overclocking.

Have to admit, the difference between 1st and 2nd, i dunno. Except -12 vs -20. You are missing the model number for the first one to compare it exactly. Based on the price i would guess the 1st one is the "normal" edition, while the 2nd looks to be DHX edition. Has some heatsink fins on top. Your retailer prolly has some pictures online, compare there. Based on cooling, i would say the DHX are a safer choice when using more vDIMM. But then again, thats only needed when overclocking, which you seem to be not doing (yet).

I would go with the third lot personally as it has the tighter timings which generally translates into more overclocking headroom as they will run faster with slacker timings.

As you are looking to o/c in a years time (why then...?) I would go with the cheapest and put your hard earned $ elsewhere.

In a years time it is likely that DDR3 (http://www.anandtech.com/memory/showdoc.aspx?i=2989) (or http://en.wikipedia.org/wiki/DDR3_SDRAM) may be more available and better value and hell you may want to upgrade your mobo and cpu (with prices expected to go south shortly)

Have you checked out Clunks guide for O/C - may not be exactly as per your mobo but it gives you a very good start. http://forums.hexus.net/showthread.php?t=103676

Thanks a lot for the input guys.
Since I have decided to go with a budget and since I have decided that I will most likely upgrade in a 2yrs time, when Penryn/Nehalem+DDR3 will be the standard, I guess then that going for option #1 is a balanced choice for me.

Thanks again.