Tips for a slight overclock (ram + fan)

Below is my config, not too bad, but I would like to get into overclocking gently.

Asus P5Q-E
Intel E8400 + radbox
2x1GB Corsair 667 + 2x1GB Corsair 800
Sapphire HD4850 Dual Slot/ViewSonic vx2260wm 22" Full HD
2 DiamondMax21 160GB/250GB, 2 DiamondMax22 500GB
Case: BigMax Max In Power + LC Power LC6550, 550W
Vista Ultimate SP1 64 Bit

Well, I know that I have to change my RAM to take 2 x 2GB PC8500, OCZ I thought of but if you advise me better I'm interested.

Then my big problem lies in the processor fan, I know nothing about

You should tell us what do you mean by "slight overclock" & your budget.

You do not really find any fan of LC power (known to make components well below the requirements for what it offers in watts)

550W? yes its MUST

Light? Genre overclocking too powerful, which allows me to stay in air-cooling, with a budget ram + fan Rs. 6500, I'd like to climb to 3.5. I am in the real with this budget, knowing that the ram should be around 3250 - 4000? After I am far from the truth, tell me

The goal is to keep my config for quite some time (I use to play), even though I know that in its current state it still has the future, I am curious about overclocking, so I'd like to start now.

For power supply, I understood that my choice was wrong, I change it when I shall be buying another graphics card later?

I advice you to change your power supply rather than buying what overclock, because your power supply may present with a grill and overclock more grilling component

I understand that my LC was not a Corsair, but I did not think it was that kind of power supply.

So what power supply would you advise me, knowing that I have no idea of the power required (400, 450, 500 +)? I wanted to change it by buying a 2nd graphic card Xfire

450W is sufficient if you do not make a crossfire. But if you loved the power supply modular, you need to move the HX520.

precision for the crossfire:
the E8400 OC @ 4GHz and crossfire of HD4850 @ stock. But where I begin to doubt, if you account is also oc graphics card, which may pose some concerns