Suggestions on what i should do

[Johnny123]

Well my old mainboard (with the G31 chipset) I retired early for many reasons (the main being it is a huge bottleneck for my HyperX DDR2-800 and the E8200). So i've got this one (Things that lagged on the old board dont on this one, so i'm quite happy already, It also supports my big beefy graphics card i'm using).

GIGABYTE - Product - Motherboard - Specification - GA-P31-DS3L (rev. 1.x)

On the specs for it, it mentions it supports 1066Mhz RAM frequency when it's overclocked. DDR2 1066(O.C.)

Now, should I buy 4gb of DDR2-1066 (2x 2048Mb 2Gb DDR2 1066 Memory Kingston HyperX 8500 Kit C5 - KHX8500D2K2/2G) Also what sort of speed gain would I achieve?

Or add another 2gb of what i've already got (1x 2048Mb 2Gb DDR2 800 Memory Kingston HyperX 6400 Kit KHX6400D2LLK2/2G)

What do you guys think? I'm kinda eating the 2gb ram quite heavily from quite serious multitasking (i.e having more than 20 tabs open in firefox while watching a movie (full HD 1080p on the second screen) or playing a game or doing other misc things that i might do).
So i do need an extra 2gb ram, but should i go all out and buy the higher performance RAM (I've already spent most of last weeks paycheck from all the other parts i've bought in the last few weeks)?

[ironman]

I see that board has a load of memory warnings on it so if you wanna ram it up to 4gb -its limit - one more 2gb module of the same cheaper ram would be the way I 'd look although with xp you won't see all of it.
Also since vista improving heavy users will want 8gb ram in new setups - 4x 2gb's - just a thought especially since ddr3 getting cheaper and faster by the month.

[mv2devnull]

Also what sort of speed gain would I achieve?

FSB of 1333 is a quad-bump from 333 isn't it?
And 1066 double data rate ram actually uses 533 clock.
Thus, that ram would fill the northbridge about 16/11 times faster than NB talks to CPU. Already a ddr2 667 runs at 1:1 with FSB.

There are benchmarks around, showing no or some speedup from having faster than 1:1 ram. Part of it is from decreasing latency. And in your case the additional ram naturally decreases disk IO too. But hard to say how much.