New PC Build Gaming and General Use

Just out of curiosity, why don't you want to use the max resolution of the monitor for games?

This is a lot better of a graphics card for only a moderate increase in price:
http://www.amazon.co.uk/01G-P3-156 [...] 298&sr=1-8
scratch that, on the search page it was listed at 130 quid, must have been a bug.

Check out scan.co.uk, they tend to be a cheaper then overclockers.co.uk and you can get free shipping if you do a bit of research.
Personally I make my list then buy the parts as they come up on scan's today only page over the course of a week. They tend have a gpu day, a cpu/mobo day, etc.

I did this for a £400 system I made for my brother and managed to save about £50 (which I could spend on getting a better gpu).

+1 to scan they always work out cheaper than overclockers.

All from Scan

£145.15
LN36726
Intel Core i5 2500K Unlocked, S1155, Sndy Bridge, Quad, 3.3GHz, HD3000 IGP 850Mhz, 6MB Cache 95W Retail
£145.15 £174.18
£90.68
LN40545
Asus P8Z68-V LE, Intel Z68, S 1155, DDR3, SATA III - 6Gb/s, RAID SATA, PCIe 2.0 (x16), VGA On Board, ATX
£90.68 £108.82
£31.16
LN40235
8GB (2x4GB) Corsair DDR3 Vengeance LP Cerulean Blue, PC3-12800 (1600), CAS 9-9-9-24, XMP, 1.5V
£31.16 £37.39
£111.68
LN42440
1GB XFX HD 6870, 4200MHz GDDR5, GPU 900MHz, 1120 Cores, EyeFinity, HDMI/ 2x mini DisplayPort/ 2x DVI-I
£111.68 £134.02
£36.95
LN22762
Antec 300 Three Hundred, Black Mid Tower Ultimate Gaming Case w/o PSU (New Version)
£36.95 £44.34
£45.60
LN35693
600W PSU, Corsair Builder Series CMPSU-600CXv2UK, 80% Eff', 80 PLUS, EPS 12V, Quiet Fan, ATX v2.3
£45.60 £54.72
£11.29
LN39293
Samsung WriteMaster SH-S222AB/BEBE 22x DVD±R, 12x DVD±R, DVD+RW x8/-RW x6, SATA, Black, OEM
£11.29 £13.55
£54.59
LN40846
500GB Seagate ST500DM002 Barracuda SATA 6Gb/s, 7200rpm, 16MB Cache, 8.5ms, NCQ
£54.59 £65.51
£96.22
LN36525
22" Viewsonic VX2239WM Black HDMI/DVI/VGA 1920x1080, 100,000:1, 300 cd/m², 2ms Speakers
£96.22 £115.46

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Net Total
Carriage
VAT
£623.32
£13.98
£127.47
Total£764.77

Ok heres my quick run down

Processor: i5-2500K - Great for the money and ideal for your budget.

Motherboard: ASUS 1155 SABERTOOTH P67 REV 3.0 S/L - I'm not upto date on the 1155 mobo's, but this one seems a little gimmicky to me. I've been hearing great things about the H76 boards.

Memory: G-Skill 8GBXL Ripjaws X for Intel Sandybridge Platforms DDR3 PC12800 1600MHz 8GB Kit - Decent ram, decent price.

Graphics Card: EVGA Geforce GTX 550Ti Superclocked - For your budget I'd spend a little more and get something like a 6850 or 6870. For a £600 budget I'd be looking in the £150 range.

HDD: I'm a fan of the Samsung F3. However with the current prices I'd be temped to buy a ssd for the boot drive and use an old hdd for storage.

Optical: Which ever is cheapest and matches the case.

PSU: Antec TruePower New Modular 550W '80 Plus Bronze' Power Supply - good pick, scan has it £10 cheaper.

Monitor: Asus VE228H 22" Widescreen LED Multimedia Monitor - I'll admit my knowledge of monitors isn't the best. I'll let someone else advise you on this.

Case: NZXT Phantom Enthusiast Full Tower Case - The case is mainly down to personal preference. If I was going to drop that much on a case it would have to be something like the Antec P183. Its a massive chuck of your budget....