Any advice about this build

[skoobedoo]

Hello, have been reading this forum all week and have decided to build new pc next week and need your advice about what i have chosen so far and parts not yet decided on.
I use my pc for Photoshoping and video/audio converting, and would like to play FPS games also. I don't mind overclocking a little but not into it big-time. I am in the UK so it would have to be from ebuyer, novatech or cclonline. Will go elsewhere if price/product is right.
Here is what i have narrowed it down to so far... budget is around £900

Case .. Coolermaster CM 690 £64.99
MoBo.. Asus PQ5 Delux £146.83
PSU .. Corsair 650W TX £65.78
CPU Cooler .. NOCTUA NH-U12P .. 45.00
HDD .. WD Caviar Black 640GB WD6401AALS 32Mb .. £60.51
GPU .. SAPPHIRE Radeon HD 4870 -1 GB £220.00
CPU .. Intel Quad Q9550 £238.54 or E8500 .. £156.55
Mem .. No idea, 2x2GB of ??
DVD R/R Sata .. ??

Have XP and Vista 64
Will go for a 24" Monitor next month

So what do you think? For my requirements should i change anything, i know duo is the best for gaming, but will this quad be better for all round use?
Will probably add another 1TB HDD later for storage.
Your advice will be much appreciated.

 

[NeoCrisis]

Solid build
mem id go with either corsair or crucial if you wanna future proof it go with an x48 board for DDR3
as far as gaming goes theres really not much noticeable difference between quads and dual cores. But for Video encoding quad cores are the way to go. It takes me less then 80 mins to encode a 2hr SD movie in h264/mkv. With my old dual core it took almost 3hrs