Memory Recommendation, could use some pointers

Hello there, I am looking for some advice on upgrading my computers memory. My current system specs are as follows:

Motherboard: Gigabyte P35-DS3L
Processor: Intel(R) Core(TM)2 Duo CPU E6750 @ 2.66GHz (2 CPUs)
Memory: CORSAIR XMS2 1GB 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) 2046 MB ram
Video Card: NVIDIA GeForce 8800 GTS (latest drivers)
Power Supply: 600W PSU, proper rails for the video card.
Hard Drive: WD Raptor 150 GB, 1.5 Gb/s, 16 MB Cache, 10,000 RPM

My current memory is: http://www.newegg.com/Product/Prod [...] 6820145153
CORSAIR XMS2 1GB 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) - With a CAS latency of 5.

I was looking at: http://www.newegg.com/product/prod [...] 6820231065
G.SKILL 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) - With a CAS latency of 4.

I have been doing research on what sets memory apart from eachother, and through that, I am trying to figure out whether the difference in cost would be worthwhile or not. So far I have seen that a difference of 1 in CAS latency would not be worthwhile, but I'd still like more opinions, maybe I am missing something between the two listed. I am big into gaming (mostly World of Warcraft), so performance is everything to me. If someone could explain to me whether or not it would be worthwhile to spend so much more on memory, it would be appreciated. Also, if there are any other DDR2 recommendations that would be better then the one listed, that would be cool as well. Thank you!