New memory, speed Vs. amount Vs. ratio.

[KCN]

Hi Guys,
I'm thinking about getting some new ram but need a bit of advice as i think i went a bit over the top last time.
I have a X38 mobo (maximus formula SE) and a Q6600, i do a bit of over clocking but nothing too silly really, currently at 9*400 which it all seams happy at with most things set at auto (i really don't seam to have the time to properly fiddle and stability test these days). I've been water cooling for a good few years now but it's now become more of a means to keep the rig quiet and stable as opposed to rinsing every last MHz (ah the althlon XP pally days).
As i currently have 2GB of OCZ 9200 flext (in the loop parallel to the NB)
1. Would i see a significant increase if i upgraded to the 4GB?
2. As i'm running a quad and am unlikely to get much FSB over 450-500 is it worth getting 1150 ram anyway, how much extra performance will i see running it over 1:1?
3. Would it be better to get an 8GB kit rated at 800-1066 for about the same price although this would take all 4 slots and with the the NB and quad is this going to make overclocking a lot harder.
Main use for the rig is Gaming and watching movies with the odd HD DVD.

[ratbuddy]

This isn't the answer you are looking for, but based on your uses (gaming and movies) the thing that would give you the most performance rather than increasing memory is to sell the Q6600 and grab an E8400 for about what you can sell the Q for, and run it 400mhz higher. What OS you running?

[KCN]

Currently running Vista ultimate 32 but am tempted to eperiment with 64 or go back to XP (either 32 or 64). I do a bit of multi tasking but as most of my remote work has now become become IX based it's not much more than Putty and firefox at the same time. Most of my gaming is done at the same time as watching divxs (game on screen 1 at 1920*1200 and video on screen 2 at 1440*900) is this actually taxing even 3 of the cores? because if not then i think i might have to investigate a E8X00 as even though the SLACR is a nice ofverclock i can't push the quads fsb as high as a dualie and as you say overall headroom would be higher due to the reduction of power/heat.