Corsair: 3 DDRPro types, What should I get?

Question

My 2x256K RAM is about 20MB-200MB short when running certain games. So Im going to get 2x512s. Corsair pros seem to be a good choice as they have very low latency.  From what I hear, low latency is how AMD users make up for not having the bandwith Intel chips have. (I know I have a 333 FSB, next year Im going to a 3200+ CPU):
However, this is confusing me. Corsair 3200PRO-series sticks seem to have three types. XL,LL, and C2.  I orignally wanted the XL bc it had the lowest latency(2-2-2-5) vs. LL (2-3-2-6), C2(2.5-3-3-6). Why all the choices?
Here what I can tell: The XL only comes in twins. The LL and C2 come seperately. The C2 can appearantly work on "intel platforms". Then it get real confusing, because if you look at the individual spec pages, only the LL mentions it can be used on "nForce 2 Ultra". Cant they all given that they all list at DDR400?
http://www.corsairmicro.com/
What should I get?  I read that DDR only makes a 3-5% difference. So I would forgo the twins, BUT they only sell the XL (2-2-2-5) latency in a twin pack. So there may be more of a gain here in the XL series.
Will I notice the difference in latency of seperately buying 2 LL(2-3-2-6) sticks over the XL(2-2-2-5) twins, or is this just a paper gain that no one really notices?
If Im doing overkill and can accomplish a gig DDR 400 at a lesser cost, please let me know. The "bling" lights on the Pro sticks is not that much of a purchase factor. I just want speed.
Sorry for the long first post. I couldnt find anything upon several searches.
FWIW: Thanks to Wonkaboy, Raven, the guy with the robot in his sig, and everyone else who contributes. I now have  the fastest and most stable computer I have ever used or owned. I had no problems bc of the compilations in the stickys. Very good work on those.
(EDITED IN AFTER POSTING)
K7n2 Delta - LISR
AMD 2600 (AXDDA26000DKV3D 9486085287232)
Antec True480W +5V/38A, +12V/22A, +3.3V/30A; MaxW 480
MSI ATI 9800 Pro
Corsair XML 256 twins 2700 LL(333FSB)
MSI Combo 48x-32x-48x; 16xDVD
Linksys Wireles PCI Adapter
DDR mode/Aggressive BIOs setting/ No OC.

Answer 1

Wonkaboy conviced me that with the costs of prosticks (and a AMD3200+) I would be halfway to another system:
I went to get the same model # as min current twins (2700LL 2-2-2-5), but corsair doent make 512K 2700LL . So I had to settle for 512K 2700C2(2-3-3-6).
If I read the above link right Im only looking at a 1-2% difference anyway
The auto detect was configured 3-3-3-7   . So I went in and changed it to 2-3-3-6.  I cant get it near 2-2-2-5(but I didnt toy with voltage or any other FSB parameters).  I may try 2-3-2-6 but Im giving up after that. I tried other-lower settings but it didnt work. Again, Im to scared to start toying with the voltage, I dont know enough and dont want to fry the system.
Any comments are appreciated as far as setting the ram speed. Id like to get 2-2-2-5, but it looks like I may settle for 2-3-3-6.
My computer runs much better now that it has enough ram to not bother with page file swaping.
Thanks Wonkaboy and Raven!
(EDITED IN AFTER POSTING)
K7n2 Delta - LISR
AMD 2600 (AXDDA26000DKV3D 9486085287232)
Antec True480W +5V/38A, +12V/22A, +3.3V/30A; MaxW 480
MSI ATI 9800 Pro
Corsair XML 256 twins 2700 LL (slowed to run at 2-3-3-6)
     Plus: Corsair 512K 2700C2 (running 2-3-3-6)
MSI Combo 48x-32x-48x; 16xDVD
Linksys Wireles PCI Adapter