Crucial vs Crucial and a few other questions

[bh31]

I'm looking to build a new system and wanted to know which would be better for overclocking

Crucial Ballistix PC2-8500 DDR2 2GB 2X1GB DDR2-1066 CL5-5-5-15 240PIN DIMM Dual Channel Memory Kit
or
Crucial Ballistix PC2-6400 2GB 2X1GB DDR2-800 CL4-4-4-12 240PIN Dual Channel Memory Kit

I was going to buy the Corsair Dominator 8500 but its a lot more expensive than these Crucial sticks. Here is what my system will look like:

EVGA 780i SLI
Intel Q6600
EVGA 8800 GTS 512 crysis edition x2 SLI
OCZ GamerXtreme 700W
4 hard drives
Thermalright ULTRA-120 Extreme 6 Heatpipe Cooler LGA775 Heatsink
Scythe S-Flex 120mm fan for CPU and 4 other case fans
DVD Writer

So I have 3 questions
1. What RAM will work better for OCing?
2. Does the 8500 RAM work better then the 6400RAM or do the timings mean more c4 to c5?
3. if I get any of these can I get 2x2GB for 4GB or should I only get 2x1GB so less stress on the memory controler?

On a side note I came across this http://www.evga.com/support/mbmem/ and don't see the Crucial Ballistix PC2-8500 DDR2 2GB 2X1GB DDR2-1066 CL5-5-5-15 240PIN DIMM Dual Channel Memory Kit listed, anyone else have a 780i board and use these?

Thanks!

 

[deranged]

I have 2x1gb of Crucial Ballistix PC2-8500 running on a p5k duluxe.
On the factory rated voltage of 2.2 I have them running at 1000mhz, with 4-4-4-12 timings. I have also had them @ 1200/5-5-5-15 also @2.2 volts. All tested with memtest then prime95.25 blend, for northbridge/memory stability without 1 error. This ram is fast and very overclockable, I would go with pc2-8500. If going with 4gb of memory, go with 2x2gb, as it is easier on the memory controler, easier to overclock, and way easier to upgrade. Not sure if Crucial makes 2x2gb in 8500 ddr2 however...

 

[zenmaster]

Either will work equally well.
No need to spend anything special on your DDR2-800 since straight DDR2-800 will take the Q6600 to 3.6Ghz which is about it's max.