Deathrow

I will be using my pc for gaming and vista, need quick advice as Im buying tonight.

Heres the rig:
OS: Windows Vista 64 bit
Cpu: Intel core 2 Quad Q6600 w/ Thermalright Ultra-120
Mb: Asus P5N32-E SLI
Mem: ???
Hd: 150Gb WD Raptor
Gpu: 768 XFX GeForce 8800GTX
Drivers: Optiarc cb-1100GNB
Mon: Samsung SM 22" Widescreen SM226BW
Psu: Antec TruePower Quattro 850w PSU
Case: Antec P182 Performance 1

So which memory should I buy out of:

I was thinking of:

OCZ DDR2 PC2-6400 Reaper Enhanced Bandwidth Edition
As it has 800MHz DDR2 and EPP 4-3-3-15

Or these:

2GB Corsair Twin2X 2048-6400PRO

OCZ DDR2 PC2-9600 FlexXLC Edition - I dont have water cooling btw.

4GB Corsair TWIN2X4096-6400C5

OCZ DDR2 PC2-6400 Platinum 4GB Dual Channel

Corsair 4x1GB QUAD2X4096-6400C5DHX

OCZ DDR2 PC2-9200 Reaper HPC Edition

I was goin to buy 2x 1GB Corsair Dominator PC-8500 but was told the graphics card and quad core cpu would be the main areas and memory wouldn't make alot of difference.

Or anything else from this site

__________________
O/S:Windows Vista Home Premium 64Bit SP1
CPU:Intel C2Q Q6600 (G0) 3.65GHz w/Thermalright Ultra-120
MB:XFX 780i P04 Bios
RAM:4GB OCZ DDR2 Reaper EB Edition 810MHz|4 3 3 8 2T
HD:150GB WD Raptor
GPU:XFX 9800GX2 1024MB|700MHz GPU|2.2GHz Mem|1750MHz Shader
Monitor:Samsung 22inch Widescreen
Sound:SB X-Fi Xtreme Gamer
Input:Steelseries 5hV2 Headset|HABU Gaming mouse|Saitek Eclipse2 Keyboard|Tagan BZ 1300W PSU | 3DMark06:18,144