Improves performance switching to 8 GB

After running the rig for some time now, I can say to be quite satisfied with the PC assembled. Thanks to your valuable advice.

But now I have the "itch" to move from 4 to 8 gig of RAM. Will I have some improvement in performance?

Currently I have:

Mobo: Asus P5K
Chipset: The P35
RAM: 4x1 GB OCZ 800MHz DDR2
VGA: Nvidia 8800 GT 512 mb
OS: Vista x64

To be honest I have also asked Corsair which would be geared towards .. and they told me that it would be preferable rather take 2 of 2 gb (Dominator type) so as to maintain 4gb total climb but the frequency of a ram 1066. This is possible even with 4 modules but should also increase the voltage for use with "dangerous" overheating and instability.

What do you think..own experience and / or indirect?

8 gigs do not make a big difference today, certainly attach between 1 or 2, but the measure will certainly DDR3 standard.

The frequency is right, 8 gig will not exploit them, exploiting much more the transition from 800 to 1066.

Overclockable 4 benches x2GB 800MHz up to 1066 is without a dedicated cooling.

The transition to 8 gb brings you no benefits, unless they use the computer for editing or graphics professional, but exclude the use of configuration seen
so it's much better to go more often.

With the courteous responses. These are in fact the only application that puts pressure on my PC :

Flight simulator: FSX
Photoshop CS3
and sometimes Pinnacle Studio.

So it would be preferable to the 2 benches 2 gigs
What DDR2 recommended for maximum ... in my conditions?

But it also depends on what you have now. Its fine if you go to 1066 or improvements you have them better if you do certain things:
In the sense that the ram from 800 to 1066 are made especially for overclock, If you do not overclock the only way to increase a little performance is to get off the ram to their cpu bus, and then bring them in sync 1:1 and then the timing tuning.
Eg. in your case to bring the ram in synchronous with 333 (667 mhz) and thus reduce the frequency, timing and lower to be faster, much more frequency (800 mhz) does not serve you if you do not overclock. Then this would be a another way to exploit