£600 approx gaming PC MMO and FPS

APPROXIMATE PURCHASE DATE: Within the next month

SYSTEM USAGE FROM MOST TO LEAST IMPORTANT: MMO's specifically Aion maxed, and a decent GPU for any new first person shooters.

PARTS NOT REQUIRED: Keyboard, Mouse, Monitor, Speakers

PREFERRED WEBSITE(S) FOR PARTS: Ebuyer, Overclockers, Scan COUNTRY OF ORIGIN: UK

PARTS PREFERENCES: AMD CPU, Decent branded PSU

OVERCLOCKING: Defo on CPU, poss on RAM and GPU

SLI OR CROSSFIRE: Prefer not

MONITOR RESOLUTION: 1680 x 1050

ADDITIONAL COMMENTS: This will be my 2nd build, for my cousin. First was using AMD CPU and ATI card, overclocked RAM and CPU. He wants to spend around £600 and he wants his PC to be better than mine lol. The parts i picked out as a rough idea are as follows:

Case Antec 300 £39.99
CPU AMD Phenom II X2 550 Black Edition 3.1GHz 6MB L3 Cache Socket AM3 Retail Boxed Processor £73.74
GPU Sapphire HD 5770 1GB GDDR5 Dual DVI, HDMI Display Port PCI-E Graphics Card £130.61
PSU - Corsair 650W TX Series PSU - 120mm Fan, 80+% Efficiency, Single +12V Rail £69.00
Mobo Sapphire PC-AM2RS790GX 790GX Socket AM2+ onboard graphics 8 channel audio ATX Motherboard £78.55
RAM OCZ 4GB (2x2GB) DDR2 1066MHz/PC2-8500 Gold Memory £94.99
HSF Scythe Shuriken Quiet Low Profile Socket 1366, 478, 775, 754, 939, AM2, AM3 Processor Cooler 24.82

Total £511.70 which leaves a few quid spare for an OS and some flashy neon case fans.

Case is pretty much non negotiable as i really like the Antec 300 and i cant see anything beating it for Value. The CPU id like to try and clock to 3.7 and unlock the other 2 cores which i saw that you could do with the right motherboard. GPU....open to suggestions i just picked the current most popular on Ebuyer. The RAM is a concern.. I've gone 1066Mhz as i seem to remember that speed works better with the Phenom 2's....but its been a while and it seems hellish expensive. Should i just stick with the 800 MHz which can be picked up for 35-40 quid?
The PSU is probably overkill going on what i read about the GPU being low draw, but he would like the option to xfire, and id prefer to work with a single rail.

Comments appreciated, thanks in advance.

Edit: Ow yea we got the HDD / Media drives sorted too so just need opinions on the parts above please.

if u r OC ur CPU i'd go for a quad core. games will eventually take advantage of all cores.

Bump...still hoping for some advice...

if your going for a 5770 then why not:

this xfx one for£126.01
or this power color card for £123 (being reference design im assuming brand doesnt really matter)

lol - I see what you were saying over in the UK general section now. A couple of years ago and you would have had at least 100+ replies.

http://www.scan.co.uk/Products/450 [...] -certified