Assuming that you will run something like 12*200 (2.4 GHz) or 12,5*200 (2.5
GHz) the low latency stuff would be the best/fastest for your system.

I have a XP-M on a nForce2 mobo and if I would buy new ram today I would
buy 2*512 of any ram based on the new Samsung chips. Most of the big brands
have them. There are many reviews you can read. Here is one:

http://www.anandtech.com/memory/showdoc.aspx?i=2145

So if you must have Corsair then the 3200XL Pro would be my recommendation.

/Ville